Multimedia Selection

home *** CD-ROM | disk | FTP | other *** search

/ Multimedia Selection / Multimedia Selection Volume One - CD-ROM / MULTIMEDIA SELECTION____________.ISO / grafica / dos / alchm17 / manual.exe / ALCHEMY.DOC

Wrap

Text File | 1993-06-23 | 381.9 KB | 12,981 lines

Image Alchemy Version 1.7 Handmade Software, Inc. Notice Handmade Software, Inc. makes no warranty of any kind either expressed or implied. In particular we make no warranty as to merchantability or fitness for a particular purpose. In no event shall Handmade Software, Inc. be liable for any errors contained herein or for incidental or consequential damages in connection with the furnishing, performance, or use of the Image Alchemy product or documentation. This document contains proprietary information which is protected by copyright. No part of this document may be photocopied, reproduced, or translated without the prior written consent of Handmade Software, Inc. The information in this document is subject to change without notice. Copyright (c) 1990-1993 Handmade Software, Inc. All Rights Reserved ii Printing This manual was created using Microsoft Word 5.1a history on a Macintosh II computer. First Printing Handmade Software, Inc. 15951 Los Gatos Blvd., Suite 17 Los Gatos, CA 95032 +1 800 358 3588 +1 408 358 1292 +1 408 358 2694 fax +1 408 356 3297 BBS Internet: hsi@netcom.COM CompuServe: 71330, 3136 iii Author credits Image Alchemy Marcos H. Woehrmann was written by Allan N. Hessenflow David Kettmann Paul H. Yoshimune Other credits Marc Schneider Who provided assistance with the Sun implementation of Image Alchemy including Beta testing and answering questions about the internal format of Sun Raster files. Jack, Norm, Who proofread the manual (any remaining misteaks Erwin, and Dave are because we made changes after they read it for the final time). Everyone Else Who gave us advice and assistance and especially to those people who sent us sample image files. iv Trademarks Image Alchemy is a trademark of Handmade Software, Inc. All other products or services mentioned in this manual, including: IBM PC, IBM PC AT, 80286, 80386, 80486, VGA, 8514/A, Paradise, Everex, Trident, Video 7, Tseng Labs, Western Digital, MS- DOS, PC-DOS, SPARC, Sun, SPARCstation, SPARCserver, SunOS, Targa, PostScript, EPS, Encapsulated PostScript, GIF, ILBM, IFF, Macintosh, Silicon Graphics, SGI, PCX, TIFF, Windows, Windows BitMaP, EGA, PCL, HP, AI, PS/2, HAM, PC Paintbrush, MacBinary, PHIPS, NeXT, C- Cube, Storm Technology, Radius, ColorSqueeze, VFCtool, Amiga, CompuServe, LaserJet, Melior, and Gill Sans are trademarks, registered trademarks, service marks, or registered service marks of their respective companies or organizations. Even though they are never mentioned in this document, you should know that Yellow Pages is a registered trademark in the United Kingdom of British Telecommunications plc., and may also be a trademark of various telephone companies around the world. v Contents ------------------------------------------------------------------- Chapter 0 Introduction..................................1 About This Manual.............................2 Pathnames.....................................3 Wildcard Expansion............................3 Chapter 1 Installation Introduction..................................4 MS-DOS Required Equipment..........................5 Optional Equipment..........................6 Packing List................................7 Installation Instructions...................8 386 for MS-DOS Required Equipment.........................11 Packing List...............................12 Installation Instructions..................12 Unix Packing List...............................14 Installation Instructions..................14 Chapter 2 Introduction Basic Instructions...........................16 Filename Limitations.........................17 Output Path Name.............................18 Option Files.................................29 Multiple Runs of Alchemy.....................21 Chapter 3 Graphical User Interface (MS-DOS Only) Introduction.................................23 Menus File.......................................24 Resize.....................................27 Contents 1 Palette....................................27 Colors.....................................28 Dither.....................................28 Chapter 4 Output Options Introduction.................................30 MacBinary....................................32 Other Information............................32 Image File Formats ADEX.......................................34 Alpha Microsystems BMP.....................35 Autologic..................................36 AVHRR......................................37 Binary Information File....................39 Calcomp CCRF...............................41 CALS.......................................42 Cubicomp PictureMaker......................43 Dr. Halo CUT...............................45 Encapsulated PostScript....................46 ER Mapper Raster...........................47 Erdas LAN/GIS..............................49 First Publisher ART........................50 Freedom of Press...........................51 GEM VDI Image File.........................52 GIF........................................54 GOES.......................................56 Hitachi Raster Format......................58 HP Printer Command Language................59 HP Raster Transfer Language................63 HP-48sx Graphic Object GROB................66 HSI JPEG...................................67 HSI Palette................................68 HSI Raw....................................69 IBM Picture Maker..........................70 IFF/ILBM...................................71 Img Software Set...........................72 JPEG/JFIF..................................73 Jovian VI..................................76 Lumena CEL.................................77 Macintosh PICT/PICT2.......................78 MacPaint...................................79 MTV Ray Tracer.............................80 Multi-Image Palette........................81 OS/2 Bitmap................................82 PCPAINT/Pictor Page Format.................83 PCX........................................85 PDS........................................88 Portable BitMap............................89 Puzzle.....................................91 Q0.........................................92 2 Contents QDV........................................93 QRT........................................94 RIX........................................95 Scodl......................................96 Silicon Graphics Image.....................98 SPOT Image.................................99 Stork.....................................101 Sun Icon..................................102 Sun Raster................................103 Tagged Interchange File Format (TIFF).....105 Targa.....................................107 Utah Raster Toolkit.......................108 Vivid.....................................109 Windows Bitmap............................110 WordPerfect Graphic File..................113 XBM.......................................114 XPM.......................................115 XWD.......................................117 Chapter 5 General Options Introduction................................118 Conserve Memory.............................119 Display Image Stats.........................120 Do Not Alter Output Filename................121 Help........................................122 Overwrite...................................123 Program Information.........................124 Quiet.......................................125 Warnings....................................126 Wildcard....................................127 Chapter 6 Colour and Palette Options Introduction................................129 Black and White.............................130 Colours.....................................131 Dither......................................133 EGA Palette.................................135 False Colour................................136 Gamma Correction............................137 Match Palette...............................139 Negate......................................140 Palette.....................................141 Palette Selection...........................142 Spiff.......................................144 True Colour (15 bits).......................146 True Colour (16 bits).......................147 True Colour (24 bits).......................148 True Colour (32 bits).......................149 Undercolour Removal.........................150 Uniform Palette.............................151 Contents 3 Chapter 7 Scaling Options Introduction................................152 Flip Image..................................153 Preserve Aspect Ratio.......................154 Scale Image Horizontally....................155 Scale Image Vertically......................157 Specify Image Aspect Ratio..................158 Specify Image Resolution....................160 Chapter 8 Viewing Options (MS-DOS Only) Display Hardware............................162 Offset View.................................165 View Image..................................166 View Image in True Colour Mode..............167 View Scaled Image...........................168 View Scaled Image in True Colour Mode.......169 Chapter 9 Tutorial and Examples Introduction................................170 Appendix A Answers to Frequently Asked Questions ..........................................173 Appendix B Colour and Dithering ..........................................183 Appendix C JPEG Description ..........................................187 Appendix D Customer Support ..........................................190 Appendix E Binary Information Files (BIF) ..........................................192 Appendix F HSI Raw Files ..........................................195 Appendix G Undercolour Removal Files ..........................................199 4 Contents Appendix H HSI PAL Files ..........................................202 Appendix I Acknowledgments ..........................................203 Appendix J Other Useful Software ..........................................204 Glossary ..........................................207 References ..........................................209 Contents 5 0 Introduction to Image Alchemy ------------------------------------------------------------------- What is Image Image Alchemy is a software utility that Alchemy? manipulates computer image files. Primarily, Image Alchemy converts between various graphics file formats. Image Alchemy can translate between a large variety of file formats including industry standards such as GIF and TIFF as well as vendor specific file formats such as Sun Raster and Scodl. Currently Alchemy supports over 60 different formats, and new formats are always being added; in fact, our goal is to have Image Alchemy be able to read and write every graphics file in the world. Image Alchemy can also make changes in an image. For example, Image Alchemy can re-size an image, change the number of colours in an image, change an image from colour to black and white, and change the colour space an image uses. Finally, Image Alchemy performs JPEG compression. This is a standard for image compression that can achieve much higher compression ratios than conventional compression techniques. It achieves this high compression ratio by not entirely preserving the original image (this is referred to as "lossy" compression). For further information see Appendix C, "What is JPEG Compression". Image Alchemy 1 About this This manual is divided into 10 chapters, 11 manual appendices, a glossary, references, and an index. Chapter 0 Introduction and Conventions Chapter 1 Installation Instructions Chapter 2 Introduction to Alchemy Chapter 3 Graphical User Interface Chapter 4 Output Options Chapter 5 General Options Chapter 6 Colour and Palette Options Chapter 7 Scaling Options Chapter 8 Viewing Options Chapter 9 Tutorial and Examples Appendix A Answers to Frequently Asked Questions Appendix B Colour and Dithering Appendix C JPEG Description Appendix D Customer Support Appendix E Binary Information Files (BIF) Appendix F HSI Raw Files Appendix G Undercolour Removal Files Appendix H PAL Files Appendix I Acknowledgments Appendix J Other Useful Software Appendix K Configuring DOS/4GW Glossary References Index 2 Image Alchemy Pathnames Because the MS-DOS and UNIX operating systems use different conventions for path names, users of UNIX will have to substitute forward slashes, "/", for the back slashes, "\", found in the examples in this manual. Unintentional UNIX users should also be aware that the UNIX wildcard shell they are using may be performing wildcard expansion expansion on certain characters (generally "*" and "?"). Since these are options which Alchemy uses, they need to be escaped to prevent the wildcard substitution. This is done by using a back slash, "\", before the character (so -? becomes -\?). Image Alchemy 3 1 Installing Image Alchemy ------------------------------------------------------------------- Overview Installation of Image Alchemy is simple; it involves copying the Alchemy program off of the floppy disk or tape onto your hard drive or network. You need to be familiar with the copy command if doing a DOS installation and the tar command if doing a UNIX installation. If you are not familiar with these commands you may wish to read the manuals which came with your computer or ask someone to assist you. The installation instructions are divided into different sections for Image Alchemy for MS-DOS, Image Alchemy/386, and Image Alchemy for UNIX. Please refer to the section which corresponds to your hardware. 4 Image Alchemy Image Alchemy for MS-DOS ------------------------------------------------------------------- Required At a minimum you must have the following hardware equipment and software to run Image Alchemy. Computer An MS-DOS computer equipped with an 80286, 80386, or 80486. Many of the conversions that Alchemy does are cpu intensive, so a faster computer is definitely an advantage. Memory At least 400k of free memory. Some conversions and some images require even more memory (Alchemy will attempt to use all available system memory, so if you get out-of-memory errors or warnings try removing as many resident programs as you can (also, installing MS-DOS 5.0, MS-DOS 6.0, or a 3rd party memory manager such as 386MAX or QEMM will free up more memory)). Alchemy makes use of extended, expanded, and xms memory while performing conversions. This can greatly speed up the conversion process. In general you will need as much memory as the size of the image, in pixels, being converted. For example, a 640x480 true colour image will use 900k of memory). Hard drive A hard drive with at least as much free space as four times the size of the image being converted (i.e. a 640x480 image will require approximately 1.2 megabytes of free space). Display A supported VGA, 8514/A, or XGA board, if you wish to view images. Image Alchemy 5 Supported SVGA boards include those with a VESA driver or with the Paradise, Everex, Trident, Video 7, ATI, Ahead, NCR, or Tseng Labs chipsets. Supported 8514/A boards include IBM and those with the Western Digital chipset. Operating MS-DOS or PC-DOS 3.x or greater (because of the system additional free memory available use of MS-DOS 5.0 or MS-DOS 6.0 is highly recommended). Optional The following hardware and software is optional to equipment run Image Alchemy. VESA VGA board To get full use out of viewing images on a SVGA board a VESA driver is needed. Without a VESA driver Alchemy is limited to displaying images in 320x200x256, 360x480x256, and 640x400x256 modes (and 640x480x32768 if you SVGA board is capable of 15 bit operation); with a VESA driver the resolution is limited only by your SVGA board and monitor. Resolutions up to 1280x1024x256 and 1280x1024x16 million are possible. The VESA driver is supplied by the manufacturer of your SVGA board. It may already be included in the BIOS on your SVGA board, or it may have been shipped on a floppy disk with your SVGA board. Consult the documentation that came with the SVGA board. If there is no mention of a VESA driver in the documentation contact your dealer or the manufacturer of your SVGA board; VESA drivers are currently available for VGA boards using chipsets from Cirrus Logic, ATI Technologies, Chips and Technologies, Everex Systems, Genoa Systems, Paradise Logic, Sigma Designs, STB Systems, Tecmar, Headland Technology (Video 7), Orchid Technology, Appian Technology, Trident Microsystems, and Oak Technology. 6 Image Alchemy Refer to your SVGA documentation on how to install the VESA driver. Math A math coprocessor will not affect the speed of coprocessor most operations; the only operations that use much floating point math are scaling types c and d. Packing list The enclosed diskette contains the following files: INSTALL.EXE The Image Alchemy installation program. ALCHEMY.EXE The Alchemy software. GUI.EXE The Alchemy menu interface. READ.ME A text document describing any last minute revisions. SAMPLES A directory containing sample data files and images. See the READ.ME file in this directory for further information. Image Alchemy 7 Installation 1. Insert the appropriate floppy disk in your disk instructions drive. 2. Change to the drive by typing either a: or b:. 3. Type install. This will install Image Alchemy in the c:\alchemy directory. If you would like to install on a different drive or a specific directory, you can do this by typing install followed by the location where you want Image Alchemy installed. For example: install d:\util\alchemy will install the software in the d:\util\alchemy directory. 5. You have now successfully installed Image Alchemy. 6. The file read.me contains information which has changed since the manual was printed. To display the read.me file type type read.me. Environment variable usage Temporary disk Alchemy uses the environment variable TMP to files determine where to open its temporary files. If you have a big enough ram drive you will want to specify it using the TMP variable. Be aware that Alchemy needs up to 4 times as much space on that drive as the size of the image (a 640 by 480 image requires up to 1.2 Megabytes). An example of setting the TMP variable to drive e: would be "set TMP=e:". 8 Image Alchemy Use of extended If there is enough extended or expanded memory and expanded available, Alchemy will use it instead of the memory temporary file it would otherwise use during some conversions. To use extended memory you must have an XMS driver installed in the config.sys file (such as HIMEM.SYS or 386MAX). To use expanded memory you must have a LIM 3.2 or LIM 4.0 expanded memory driver installed (such as EMM386, QEMM, or 386MAX). Alchemy's use of extended/expanded memory can be disabled. To disable the use of extended and expanded memory, set an environment variable called 'alchemy' to 'x' (type "set alchemy=x" at the DOS prompt). Note that the availability of extended or expanded memory will not allow you to convert larger images, it will just increase the speed of conversions. If you need to convert very large images we also have a 386 Enhanced version of Image Alchemy, which will allow 80386 and 80486 users to make use of the linear addressing space of those processors along with virtual memory to convert images of up to 32000 x 32000 (assuming you have enough disk space). Please contact us if you are running out of memory and are interested in upgrading to Image Alchemy/386. Checking for Alchemy will normally check to determine if there 8514/A boards is an 8514/A board installed in the computer when viewing images. However, this can cause problems with some network boards, as they use the same I/O addresses that 8514/A boards use. To disable 8514/A checking, set the environment variable called 'alchemy' to '8' (type "set alchemy=8" at the DOS prompt). Note that this can be combined with other options; for example, to disable both 8514/A checking and extended/expanded memory usage, use "set alchemy=8x". Image Alchemy 9 Limiting Alchemy will automatically choose the lowest maximum display resolution which will fit the entire image when resolution viewing images without specifying a display resolution with a VESA compatible VGA board. However, depending on the monitor and VGA board combination you have, this can be bad since the monitor may not support the particular resolution the SVGA board is trying to switch to. To avoid this problem, the environment variable 'alchemy' may now be set to indicate the maximum display resolution which Alchemy should use. Set the alchemy variable to the highest horizontal resolution which your monitor is capable of. Valid values are 1280, 1024, 800, and 640. For example, type "set alchemy=800" at the DOS prompt if your monitor only supports 640x480 and 800x600 mode. Note that this can be combined with other options; for example, to disable 8514/A checking, disable extended/expanded memory usage, and limit the viewing resolution to 640x480 use "set alchemy=8x640". You can also place this line in your autoexec.bat file. 10 Image Alchemy Image Alchemy/386 for MS-DOS ------------------------------------------------------------------- Required At a minimum you must have the following hardware equipment and software to run Image Alchemy/386. Computer An MS-DOS computer equipped with an 80386, 80486, or other 32bit Intel processor. Many of the conversions that Alchemy does are cpu intensive, so a faster computer is definitely an advantage. Memory At least 2MB of free memory. Hard drive A hard drive with at least as much free space as four times the size of the image being converted (i.e. a 640x480 image will require approximately 1.2 megabytes of free space). Viewing Images Alchemy/386 does not support viewing at this time. Operating MS-DOS or PC-DOS 3.x or greater (because of the system additional free memory available, use of MS-DOS 5.0 or MS-DOS 6.0 is highly recommended). Math A math coprocessor will not affect the speed of coprocessor most operations; the only operations that use much floating point math are scaling types c and d. Image Alchemy 11 Packing list The enclosed diskettes contain the following files: INSTALL.EXE The Image Alchemy installation program. ALCH386.EXE The 32bit version of Alchemy. DOS4GW.EXE The 32bit DOS extender used by Alchemy. ALCHEMY.EXE The real-mode Alchemy software. READ.ME A text document describing any last minute revisions. SAMPLES A directory containing sample data files and images. See the READ.ME file in this directory for further information. Installation 1. Insert the appropriate floppy disk in your disk instructions drive. 2. Change to the drive by typing either a: or b:. 3. Type install. This will install Image Alchemy in the c:\alchemy directory. If you would like to install on a different drive or a specific directory, you can do this by typing install followed by the location where you want Image Alchemy installed. For example: install d:\util\alchemy will install the software in the d:\util\alchemy directory. 4. You have now successfully installed Image Alchemy. 5. The file read.me contains information which has changed since the manual was printed. To display the read.me file type type read.me. Environment variable usage 12 Image Alchemy Temporary disk Alchemy uses the environment variable TMP to files determine where to open its temporary files. If you have a big enough RAM drive you will want to specify it using the TMP variable. Be aware that Alchemy needs up to 4 times as much space on that drive as the size of the image (a 640x480 image requires up to 1.2 megabytes). An example of setting the TMP variable to drive e: would be "set TMP=e:". DOS/4GW and Please refer to Appendix K for information about Virtual Memory configuring DOS/4GW and taking advantage of virtual memory. Image Alchemy 13 UNIX Installation ------------------------------------------------------------------- Packing list The enclosed diskette or tape is in tar format and contains the following files: alchemy The Alchemy program. read.me A text document describing any last minute revisions. samples A directory containing sample data files and images. See the read.me file in this directory for further information. Installation Use tar to copy the files from the distribution instructions disk or tape to the current directory. To install the software from diskette use: tar xvf /dev/fd0 For tape installation replace /dev/fd0 with the name of the tape device. The name of the tape device varies between different models and configurations of systems; ask your system administrator if you don't know the name of your tape device. Note to Alchemy uses the environment variable TMPDIR to advanced users determine where to put its temporary files. This is usually set to /usr/tmp or /tmp, but if you are converting very large images there may not be enough space available in the partition those directories are on. In that case you may want to set the environment variable TMPDIR to a different partition. For example, to set the temporary file directory to the directory /home/images use "setenv TMPDIR /home/images". Contact your system administrator if you have problems with Alchemy running out of disk space while converting images. 14 Image Alchemy Image Alchemy 15 2 Introduction ------------------------------------------------------------------- Basic Image Alchemy is a command-line driven program instructions with an optional menu system. Historically, Image Alchemy has been exclusively command-line driven, and a lot of information in this manual is necessary for users who prefer the command-line interface. For those users who prefer the menu interface, we have tried to indicate which sections are relevant to you and which you may safely skip. Chapter 3 is devoted entirely to the menu interface (also called a Graphical User Interface, or GUI), and explains how to use the interface as well as how Image Alchemy manages both interfaces. Options Options are the commands that you give Alchemy so that it knows what you want it to do. So that Alchemy can distinguish between options and file names on the command line, options are preceded by a dash ("-"). The only option that is required is the output file format (or the viewing option, for MS-DOS users). Image Alchemy will make reasonable decisions for all of the other options. Some options take parameters. The parameters may immediately follow the option or be separated by a space. For example, either -c128 or -c 128 is acceptable. Information on selecting options from the main menu is covered in Chapter 3. The options themselves are documented in Chapters 4 through 8. 16 Image Alchemy Note that options can appear anywhere in the command line and generally they can be in any order (certain options take parameters; in those cases the parameters must follow the option). The case of the options is significant. InputFileName The inputFileName is any valid file name. This is the name of an existing image file that you are converting from or viewing. The inputFileName is required. It may include an optional drive and/or path. OutputFileName The outputFileName is the name of the file you are converting the image to. The outputFileName is optional; if it is not specified Image Alchemy generates one by substituting an appropriate extension to the input file name. If you specify an outputFileName and it does not include an extension one will be added. The outputFileName may include an optional drive and/or path. If you do not supply a path the current directory will be used as the destination directory. OutputPathName The outputPathName is the location where you want to put the output that Alchemy will create. The outputPathName is optional; if it is not specified Alchemy places the output in the current directory or in the directory specified as part of the outputFileName. Limitations on Since on the command line Alchemy lets you filenames optionally enter a space between an option and its parameter it is possible to confuse Alchemy if one of the filenames starts with a number. In particular, if you use an option which has an optional parameter, you choose not to use the parameter, and you follow that option immediately with a filename which starts with a number, Alchemy doesn't realize that the filename is not the parameter. While it sounds unlikely that this would ever be a problem it actually happens quite often. Image Alchemy 17 For example, if you wanted to convert the file 12.gif to a Targa file with the name output.tga you would have to be careful of the order in which you specified things. If you say alchemy -a 12.gif output.tga Alchemy would misinterpret that as alchemy -a12 .gif output.tga and would generate an error. The easiest way around this problem is to always put the filenames first alchemy 12.gif output.tga -a or don't use filenames which begin with a number. Output path The output path name is the location where Alchemy will place its output. The outputPathName can be specified on the command line as part of the outputFileName if you are specifying an outputFileName. For example alchemy sample.jpg -g test.gif \images is the same as alchemy sample.jpg -g \images\test.gif However, alchemy sample.jpg -g is not the same as alchemy sample.jpg -g \images 18 Image Alchemy When using the wildcard option, Alchemy allows wildcards and multiple file names. In this case the use of an outputFileName is not allowed, but the use of the outputPathName is. See the wildcard option for more information. Using option Alchemy can read command line parameters from files files. Doing this is equivalent to typing the options on the command line. Lists of options are useful when you have commonly used commands or when you have long commands which would be hard to remember or exceed the command line limits of your operating system. To use an option file you will have to create a text file using a text editor. This file can have any name or extension you wish. To pass this file to Alchemy use the @ operator, followed immediately by the name of the text file. For example, if you frequently need to scale images to be no larger than 640x480, using 'b' quality scaling, and preserving aspect ratio, you can make a text file which looks like this (called SCALE, for purposes of this example): -Xb640 -Yb480 -+ You would then use this text file with Alchemy by passing its name along with any other options (including the output file type option). For example: alchemy @scale test.gif -g new.gif would convert the GIF file test.gif to a GIF file called new.gif, thus performing the desired scaling operation. It is also possible to place filenames and other option lists in options lists. For example, if you want to convert all of the .gif, .tif, and .tga files to JPEG files you can create a text file which looks like this (called FILES): *.gif *.tif *.tga And then use this command line to convert those files to JPEG files: Image Alchemy 19 alchemy @files -j If you wanted to scale the images at the same time you would add that option file to the command line (using the SCALE text file created earlier): alchemy @files @scale -j 20 Image Alchemy Using multiple In general, Image Alchemy will perform equally runs of Alchemy well regardless of how many steps it takes to accomplish a command. However, if you use multiple steps, be careful of their order. Sometimes you may know what you want to accomplish but not how to specify the correct combination of options. For example, you may wish to re-size a true colour Targa file that you have scanned and convert it to a 16 colour GIF file. Let's say that the input file name is file.tga and you want to generate a file with the name file.gif. In this case you could type: alchemy file.tga -Xb640 -Yb480 -c16 -g However, there would be no penalty in quality (and little in speed) if you did things in two steps: alchemy file.tga -Xb640 -Yb480 -r temp.raw alchemy temp.raw -c16 -g file.gif In this case you are telling Alchemy to use a temporary raw file called temp.raw. It turns out that Alchemy would have automatically used a temporary raw file in the first case. So, except for having to delete the file temp.raw, both uses are identical. The order of steps is important in many cases. For example, reversing the order of the two operations in the previous example: alchemy file.tga -c16 -g temp.raw alchemy temp.raw -Xb640 -Yb480 -g file would give different results. This is because the scaling operation has to temporarily convert the image to true colour, but the GIF file you are generating has to be paletted, so the second operation would re-dither the image. Sometimes you will have to perform operations using multiple steps because there are some combinations of options that Alchemy explicitly does not allow. These combinations of options are not allowed because the results would not be what you expect. Image Alchemy 21 For example, using the spiff option, -S, in combination with the false colour option, -F, would spiff the image first and then false colour it, which would give the same results as just using the false colour option. Since that isn't something that you would ever want to do, Alchemy will complain if you specify both of those options at the same time. In this case you could false colour the image first, generating a temporary image, and then spiff that image. 22 Image Alchemy 3 The Graphical User Interface (Menus) ------------------------------------------------------------------- Introduction Image Alchemy v1.7 is the first release to incorporate a Graphical User Interface (GUI), commonly referred to as a menu system. The GUI can make using Alchemy much easier for casual or infrequent users, since the various command-line arguments do not need to be memorized or even known. The GUI is actually a separate program which gets information about the conversion from the user, builds a command line for Alchemy, and then calls the actual Alchemy software. In this way, users who are familiar with the command-line structure of Alchemy will not be hampered by the menu system -- the software can be used exactly as with previous versions. The GUI will also let you view the command line parameters it uses, so that interested users can learn more about Alchemy itself and the switches it requires to perform various conversions. Starting the After installing Image Alchemy (described in GUI Chapter 1), the Alchemy executable as well as the GUI should be on your working drive. The GUI will be able to find the Alchemy executable as long as it is in either the current directory or the DOS search path. Once your path has been set, simply typing 'gui' will start Alchemy's graphical user interface. The Main Screen Upon starting the GUI, the screen will be mostly blank, except for a menu bar across the top of the screen, and two small windows at the bottom informing you of the currently selected input file and the output file type. To access the pull-down menu system, type Alt-?, where ? is the first character of the option. For example, typing Alt-F will bring down the File sub-menu, and Alt-D will bring down the Dither sub-menu. Image Alchemy 23 As you move through various options in the sub- menus, a short help message will appear on the bottom status line, giving you further information. While in the menu system, pressing Esc will abort the current menu; if you are being prompted for a value in a dialog box, Esc will abort the input, and retain the old value. Note that some sub-menu entries may be dimmed; this means that these options cannot be used at this time. This usually applies to the viewing and conversion options, which cannot be chosen without first selecting an input file. Pressing and releasing the Alt key will take you up to the menu bar and pull down the first entry (the File sub-menu, in this case). The left and right arrow keys will move between the various sub-menus. At this point, the up and down arrow keys can be used to highlight a specific option; pressing Return will select that option. If you have a mouse connected to your system, you can point-and-click through the menuing system, rather than using the keyboard. Clicking an entry on the menu bar will pull down that menu, and then clicking on a specific option will actually choose it. Alternatively, you can move the mouse cursor to the menu bar, click on a sub-menu category like File, and while continuing to hold down the mouse button, select a specific item. When you release the mouse button, that item will be chosen. Quitting the To exit the GUI, select Quit from the File sub- GUI menu. Alternatively, Alt-X will immediately quit the GUI without going through the menu system. The File Sub-Menu 24 Image Alchemy Select Input Choosing this option will bring up a listing of Image all the files in the current directory. Using either the keyboard or the mouse, you can select the input file on which Alchemy will work on. There are also listings for the parent directory and various subdirectories (if any), which allow you to move around on the drive. Clicking on the Cancel button or hitting Esc will abort the selection process, keeping the previous input file name. Note that the GUI cannot check for valid image files, since it would be too time consuming to have Alchemy process every file in the current directory. As such, it is possible for you to select a file which Alchemy itself will not recognize when a conversion or view is requested. Select Output Selecting the Output Type will display a scrolling Type window containing the different image formats to which Alchemy can output. The up and down arrow keys will move the highlight bar up and down one try, and the PgUp and PgDn keys will move the highlight bar up and down one page. Pressing Return selects the highlighted output type. The mouse can also be used to scroll through the window: clicking on the up and down arrows will move the highlight bar up and down one entry, and clicking in the scroll bar above or below the current location marker will page up and down through the list. If you select an output format that has further options (such as compression type), a further pop- up menu will ask you to pick an option. Either typing the highlighted key or clicking on the name will select that option. Image Stats After selecting an input file, selecting this option will display various information for that file, including the height and width, number of colours, and compression ratio. Other values may be displayed, if they are available, such as dots per inch (DPI), aspect ratio, and gamma. Image Alchemy 25 Viewing The next four options are for viewing the image you have selected. View Image will do a standard 8-bit view on an SVGA monitor, displaying only the center portion of the image if it exceeds maximum screen resolution. Using the View Scaled option will work similarly, except it will use Nearest Neighbor scaling to make sure the entire image fits on the screen. If you have an SVGA board and monitor capable of displaying images in true colour (15-, 16-, or 24- bits), select View True Color to take advantage of this. This option will try to view in the highest resolution possible, while displaying as much of the image as possible. Note, however, that size will take priority over resolution. For example, if you have a 24-bit SVGA card with 1MB of memory, you should be able to view in 24 bits at 640x480, and 15 bits at 800x600. So, assuming you have a 640x480 24-bit image, this option will view it in 24 bits. If, however, you have a 700x490 24-bit image, you will see the whole image, but dithered to 15 bits. Size takes priority over resolution. If you have an image larger than what your card/monitor can display in true colour, using the View True Color Scaled option will scale the image so you can view the entire image in true colour. Show Command Choosing this option will display the parameters Line which will actually be passed to Alchemy if the Convert! entry is chosen. This allows you to see what parameters need to be passed to Alchemy on the command line to enable various options. Basic/Expert This menu entry will change, depending on the Menus current status of the menu system. When first started, the GUI will default to Basic mode, which will hide many of the more obscure options Alchemy deals with. Choosing this option will then force the GUI to use the full, more advanced menus which include all possible options. When the Expert menus are being used, choosing this option will switch back to the Basic menu system. 26 Image Alchemy Convert! This should be the last option you select when converting an image; use it only after you have selected all the options you need from the various other menus. After choosing this option, you will be prompted for an output filename, with a default given based on the output type chosen. To accept, simply type Return. You may of course modify the default by typing different names, drives, or directories. The GUI will then run the Alchemy software, passing along information about the various options you have selected in the menu. Since the GUI swaps almost all of itself out of memory before calling Alchemy, you do not need to worry about not having enough memory available for a particular conversion; if the GUI runs out of memory, calling Alchemy directly from the command line will also run out of memory. If this is the case, contact us about Alchemy/386, which runs in 32-bit protected mode, and hence does not have the typical memory limitations associated with DOS applications. Quit This option will end your GUI session, and return you to the DOS prompt. The Resize The options in this sub-menu allow you to control Sub-Menu various aspects of the output image concerning its pixel size and DPI information. Along with being able to specify a certain pixel size, you can also tell Alchemy to make an image larger or smaller by some factor. Finally, you can specify the aspect ratio and DPI information from within this menu. For further information about the specific options in this sub-menu, please see Chapter 6. The Palette The entries in the palette sub-menu allow you to Sub-Menu control various aspects of the palette and its generation, including using Heckbert's algorithm, a uniform palette, or a black and white/greyscale palette. You can also tell Alchemy to use a palette from another image, or correct colours in a CMYK format using an undercolor removal file. For more detailed information about these topics, please see Chapter 5. Image Alchemy 27 The Colors The colors sub-menu primarily allows you to Sub-Menu specify the number of colours to be used in the output file. You can also generate a photographic negative of an image, as well as spiff it using one of three different algorithms. Finally, from within this sub-menu, you can modify the input, output, and palette gamma values. Please again refer to Chapter 5 for complete information about these topics. The Dither The dither menu allows you to select the Sub-Menu particular dithering algorithm to use. You can also specify whether you want a serpentine raster or some amount of perturbation; both of these options help break up visible patterns left by the dithering. For more information about the dithering options, see Chapter 5. About The The smooth graphical mouse cursor used in the GUI Graphical Mouse was implemented with SMDKIT. The Smooth Mouse Cursor Driver is copyright 1992-1993 by Andy Hakim. For further information about this software, contact: Andy Hakim 816 Pecore Street Houston, TX 77009 USA +1 713 880 3059 internet: ahakim@uh.edu 28 Image Alchemy Image Alchemy 29 4 Output Options ------------------------------------------------------------------- Introduction The one option which is always required when running Image Alchemy is the output image file type. Even if you are just re-sizing an image, or changing the number of colours in an image, Alchemy needs to know what type of image you are creating. The file types that Image Alchemy supports are listed below. In addition to the syntax required to generate the file, any known restrictions or limitations are listed. If you have trouble reading an image in one of the file formats we claim to support please contact us (see Appendix D, Customer Support). The common output options consist of a single letter. The option, like all Alchemy options, is preceded by a dash, "-". The less common output options consist of a letter preceded by two dashes, "--". With your GUI If you are using the GUI, you can select your output option from the File sub-menu as described in Chapter 3. Variations Some of the output formats have several variations; in those cases you specify which variation you want with an optional letter and/or number after the output option. 30 Image Alchemy Example The option to generate a Windows Bitmap file is - w. There are two types of Bitmap files: uncompressed and Run-Length-Encoded (RLE). To write out an uncompressed Bitmap file use -w0; to write out a RLE Bitmap file use -w1 (the default Bitmap file is uncompressed, so a -w without any parameter following it would also generate an uncompressed Bitmap file). Note that Alchemy allows spaces between the option and parameter, so typing -w 1 would be the same as -w1. Variations Be aware that the other options specified on the command line also affect the type of file that is generated. Example Within the Windows Bitmap file type there are 1 bit, 4 bit, 8 bit, and 24 bit files. Alchemy always generates a file using the best match of the file type and the output image. So, in the case of Windows Bitmap files, if the output image is black and white a 1 bit file is generated. If the output image is paletted with 16 colours or less a 4 bit file is generated. If the output image is paletted with more than 16 colours an 8 bit file is generated. And if the output image is true colour a 24 bit file is generated. You can explicitly force any of these file types by using other Alchemy options. For example, if you wanted a 1 bit Windows Bitmap file you would specify -c2 -b -w. To force a 4 bit file use -c16 -w. To force an 8 bit file use -c256 -w. And to force a true colour file use -24 -w. Identifying Image Alchemy identifies the type of file being image files read by checking various magic numbers and other information that varies from format to format. Unfortunately, some formats do not have a magic number; in those cases Alchemy guesses as to the image type. It is possible for Image Alchemy to incorrectly identify an image; if this happens please contact us. Image Alchemy 31 MacBinary When reading images, Alchemy automatically recognizes and reads MacBinary II files (MacBinary files are generated when you accidently leave MacBinary mode on when transferring a file from a Macintosh). Other Alchemy will preserve as much information in each information file as possible; this always includes the height and width of the image and the number of colours in the image. Some file types include other data, such as the name of the image, the aspect ratio of the image, the date the image was created, etc. Since most of these items are only supported by a few file formats, Alchemy discards everything but the height, width, number of colours, gamma, aspect ratio, and resolution values. Output Options The individual output options supported by Alchemy are described in alphabetical order on the following pages. The descriptions follow the template given overleaf. 32 Image Alchemy Name of format -option Overview of file format. Syntax Description of syntax. Parameter Brief description of the parameters. Those parameters which require a detailed explaination are further documented under the comments section below. Extensions The extensions commonly used for this image format. When multiple extensions are listed Alchemy writes files using the first one, but will check for files using all extensions (in the order listed). Four letter extensions are skipped on MS-DOS systems. Creator The company or individual who created this image format. Please contact them for more information on the format. Used by Programs or types of software that use this image format. Variations A list of the variations supported by Image Alchemy. Limitations Any known limitations that Image Alchemy has when reading or writing this image format. Comments Miscellaneous things of which you should be aware. Related options Other Alchemy options that affect the reading or writing of this image format. Note that -8, -24 (and, for some formats, -15, -16, and -32), -c, and -b options have an effect for most image formats and are not listed explicitly. Example Sample conversions involving this image format. Image Alchemy 33 ADEX --A ADEX files are used by the ADEX Corporation ChromaGraph series of graphics cards. Syntax --A compressionType Parameter compressionType: 0:None 1:Run Length Coded The default is None. Extensions .img .rle Creator ADEX Corporation Used by ADEX ChromaGraph cards. Variations 4 bit and 8 bit images. Comments Some ADEX files don't contain a palette; in those cases there's usually a second ADEX file which contains the palette to be used. To read those images that don't have palettes, use the -F false colour option to read the palette from a separate file. Related options -F False colour Example Convert the file test.gif to an uncompressed ADEX file called test.img: alchemy --A test.gif 34 Image Alchemy Alpha Microsystems BMP -M Alpha Microsystems BMP files are used by Alpha Microsystems. Syntax -M compressionType Parameter compressionType: 0:None 1:Packed The default is None. Extension .bmp Creator Alpha Microsystems. Used by Alpha Microsystems workstations. Variations Reads and writes 1, 4, 8, and 24 bit unpacked and packed (run-length encoded) RGB images. Limitations Reading and writing HLS images is not supported. Comments When reading an image without a palette Alchemy will generate a gray-scale palette. Examples Convert the GIF file, bigpict.gif, to an uncompressed Alpha Microsystems BMP file: alchemy bigpict.gif -M Do the same thing, but force a 24 bit image, and compress the image: alchemy bigpict.gif -M1 -24 Image Alchemy 35 Autologic --a Autologic files are black and white or gray-scale files for use with Autologic typesetting equipment. Syntax --a Extensions .gm .gm2 .gm4 Creator Autologic, Incorporated Used by Autologic typesetting equipment. Variations Graphics modes 2 (black/white) and 4 (gray-scale) are supported. Limitations Only the High Speed Interface inline format is supported. When reading, images must be preceded by a Graphics Parameter Block. Examples Convert the file input.tif to a GM4 file called output.gm4: alchemy --a -b input.tif output.gm4 Convert the file input.tif to a GM2 file called output.gm2: alchemy --a -b -c2 input.tif output.gm2 36 Image Alchemy AVHRR --R AVHRR files are used for satellite image data. Syntax --R outputType Parameter outputType 1:IDIDAS Uncompressed 2:IDIDAS Compressed type 1 The default is 1 (IDIDAS Uncompressed). Extension .sst Creators National Oceanic and Atmospheric Administration (NOAA) National Environmental Satellite Data Information Service (NESDIS) Used by IDIDAS SSTMAP IMGMAP Variations Reads 8 and 11 bits per pixel IDIDAS AVHRR files. Writes 11 bits per pixel IDIDAS AVHRR files. Limitations Level 1B AVHRR files will be supported at a later date; please contact us for more information. Alchemy discards all but the top 8 bits when reading 11 bit AVHRR files. When writing, the bottom 3 bits are padded with 0. Any graphics information is discarded when reading the file. Since AVHRR images are always grayscale, Alchemy assumes the use of the -b and -8 options when writing a AVHRR file. Comments AVHRR images contain a lot of information which is not part of the image data. This information includes the time and date the image was captured, the satellite which captured the image, the type of instrumentation used, etc. When reading AVHRR images this information is discarded; when writing AVHRR images 0 is written for all values for which data is unavailable. Image Alchemy 37 Example Convert the GOES file, florida.goe, to an uncompressed IDIDAS AVHRR file: alchemy --R1 florida.goe 38 Image Alchemy Binary Information Files (BIF) -B There are quite a few programs which produce image files which contain just pixel data. These image files do not have a header and hence do not include enough information to allow Alchemy to read them. BIF files are a method which can be used to allow Alchemy to read these images. BIF files can also be created to allow images to be read by software which expects images to be just pixels. Since required information, such as the height and width of the image, are not present in these files you must supply it. Syntax -B Extensions .bif For ASCII file describing image. .raw For actual image data. Creator Handmade Software, Inc. Used by Image Alchemy Various image processing software Variations 24 bit true colour, 8 bit gray-scale, and 1 bit black and white. Limitations Paletted files cannot be read in (a work around is to generate a .PAL file and then false colour the gray-scale image using the -F option). Comments BIF files are used to read and write files which consist entirely of image data. You have to generate a text file which describes the format of the data you are trying to read in. This file is called a BIF file. The format of BIF files is documented in Appendix E, Binary Information Files. You then instruct Alchemy to read the image data by giving it the name of the .BIF file. Related options -F False colour Examples Convert the file data to a GIF file: alchemy data.bif -g Convert the image helen.pcx to a Binary file (this will create two files: helen.raw and helen.bif): Image Alchemy 39 alchemy helen.pcx -B 40 Image Alchemy Calcomp CCRF --l Calcomp raster files are used by Calcomp thermal transfer printers, and Calcomp CCRF files are used by Calcomp electrostatic printers. Syntax --l type (lower case l) Parameter type: Thermal Transfer Printer: 0:Uncompressed 1:White Space Suppression 2:Run Length Compression Electrostaic plotter (CCRF): 6:8 bit bytes, 8 bit compression units 7:8 bit bytes, 16 bit compression units 8:8 bit bytes, 32 bit compression units The default is Thermal transfer, uncompressed. Extensions .crf .ccrf .prn Creator Calcomp Used by Calcomp thermal printers and Electrostatic plotters. Variations Black and white or CMYK. Comments If there is only black and white in the image, a 1 bit file will be generated. For colour images, the black plane will be omitted if it is empty. See the appendix on undercolour removal files for information on how to control the black content of an image. Example Convert the Targa file image1.tga to a CCRF file using 16 bit compression units: alchemy page1.tif --l7 Image Alchemy 41 CALS --c Computer-aided Acquisition and Logistics Support (CALS) files are black and white images used by the US Government as part of their transition to electronic media. Syntax --c Extension .cal Creator Defense Logistics Agency (DLA) Used by Department of Defense (DoD) Variations Reads and writes type 1 (Group 4 raster) CALS images. Limitations Document labels, such as document ID and figure ID, are ignored. Comments Since CALS files are always black and white, Alchemy assumes the use of the -b, -8, and -c2 options when writing CALS files. CALS images are Fax Group IV compressed and are therefore a good way of storing black and white line drawings and scans. Example Convert the TIFF file page1.tif to a CALS file: alchemy page1.tif --c 42 Image Alchemy CubicompPictureMaker --P Cubicomp PictureMaker files are used in broadcast- quality three dimensional modelling and animation. Syntax --P type Parameter type: 0: allow any size image 1: adjust image to 512 x 488 The default is 0. Extension .r8 (Red channel image data) .g8 (Green channel image data) .b8 (Blue channel image data) .a8 (Alpha channel image data [optional) Creator Cubicomp Corp. Used by Cubicomp PictureMaker Variations Reads and writes 24 bit true colour images. Limitations If an alpha channel exists, it will be ignored. 8-bit paletted PictureMaker files are unsupported. Comments This format is not the same as IBM Picture Maker. The option for adjusting the image size to 512 x 488 was added because Cubicomp PictureMaker does not work with images which are not of this exact size. If either the X or Y dimension is larger than 512 or 488, respectively, that dimension will be truncated. If either dimension is smaller than 512 or 488, the image will be padded on the right- hand side or bottom, as necessary, with black. PictureMaker images have either three or four separate files per image: a red, green, blue, and optional alpha channel. You specify the name of the .r8 file and Alchemy automatically generates the name of the .g8 and .b8 files When writing a PictureMaker file Alchemy will overwrite, without warning, existing .g8 and .b8 files. Image Alchemy 43 Example Convert the 24-bit JPEG image stones.jpg to PictureMaker files: alchemy --P stones.jpg 44 Image Alchemy Dr. Halo CUT --C Dr. Halo CUT files are used by various MS-DOS based paint software. Syntax --C Extension .pal (palette and header) .cut (pixel data) Creator Media Cybernetics Used by Dr. HALO III Paint Package HALO Desktop Imager Variations 8 bits per pixel Comments Dr. Halo CUT images are actually two files. You specify the name of the .cut file and Alchemy automatically generates the name of the .pal file. When writing a Dr. Halo CUT file Alchemy will overwrite, without warning, existing .pal files. Examples Convert the image test.pcx to a Dr. Halo CUT file: alchemy test.pcx --C Image Alchemy 45 Encapsulated PostScript (EPS) -e EPS files are a subset of PostScript; they may be included by other PostScript files without requiring that the importing software be able to interpret the file. Syntax -e previewType Parameter previewType: 0:None 1:Device independent 2:TIFF The default is device independent. Extensions .epsi .epi Creator Adobe Systems, Inc. Used by PostScript printers Variations Gray-scale, RGB, and indexed images. Limitations Alchemy can only write, not read, EPS images. Comments If the output is gray-scale, it will work with any PostScript device. If it's true colour, then the CMYK extensions or a level 2 device is required. For paletted files, a level 2 device is always required. Examples Convert the file input.gif to a colour EPS file called input.eps which will not require level 2 PostScript (but will require CMYK extensions), with no preview: alchemy -e0 -24 input.gif Convert the file input.gif to a gray-scale EPS file called gray.eps, with a device independent preview: alchemy -e -b input.gif gray.eps 46 Image Alchemy ER Mapper Raster --m ER Mapper files are used by ER Mapper satellite image analysis software. Syntax --m Extensions .ers for header data . for pixel data Creator Earth Resource Mapping Used by ER Mapper Variations Reads and writes single channel and 3 channel images. Limitations Alchemy cannot read 2 channel or 4 or more channel images without using the -Z option (see the comments section below for more information). Comments ER Mapper files are actually two files, one with the extension .ers and the other without any extension. The .ers file contains header information and the non-extensioned file contains the actual image data. You specify the name of the .ers file and Alchemy automatically generates the name of the other file. When writing a ER Mapper file Alchemy will overwrite, without warning, existing ER Mapper image data files. Using the -Z option it is possible to select a single channel or 3 channels when reading a multi- channel ER Mapper image. To use the -Z option follow it with a single number to indicate which channel is to be read as a grey-scale image or three numbers to indicate which channels are to be read as 24 bit colour image. See the example section below for details. Example Convert the Sun Raster file earth.ras to an ER Mapper file: alchemy earth.ras --m Image Alchemy 47 The ER Mapper file Landsat_TM_year_1991.ers contains 7 bands these examples show various ways to read selected bands out of the image: Convert the first band in the image to a grayscale Sun Raster file. alchemy Landsat_TM_year_1991.ers -Z 1 -s Convert the fifth band in the image to a grayscale Sun Raster file. alchemy Landsat_TM_year_1991.ers -Z 5 -s Convert the the image to a 24 bit, colour Sun Raster file, using band 2 as the red channel, band 7 as the green chanel, and band 3 as the blue channel. alchemy Landsat_TM_year_1991.ers -Z 2 7 3 -s 48 Image Alchemy Erdas LAN/GIS --e Erdas files are used by Erdas image processing software. Syntax --e Extensions .lan .gis Creator Erdas Inc. Used by Erdas remote sensing software. Variations Reads and writes 1 and 3 band files. Reads 4, 8, and 16 bit files. Writes 8 bit files. Limitations When writing Erdas files Alchemy does not change the extension depending on the number of bands in the image; according to the specification gray- scale files should have the extension .gis and true colour files should have the extension .lan. Alchemy always uses .lan. Comments 1 band files are read in as gray-scale images. 3 band files are read in as true colour images. The colour mapping between RGB and bands 1, 2, and 3 is Red=Band 1, Green=Band 2, and Blue=Band 3. Examples Convert the GIS file texas.gis to a Sun raster file: alchemy texas.gis -s Convert the file satellite.image to a GIS file. alchemy -b --e satellite.image satellite.gis Convert the file satellite.image to a LAN file. alchemy --e satellite.image satellite.lan Image Alchemy 49 First Publisher ART --F First Publisher ART files are black and white images used as clip art by First Publisher. Syntax --F Extension .art Creator Software Publishing Corp. Used by First Publisher Variations Black and white, 1 bit per pixel. Comments Since ART files are always black and white, 1 bit per pixel, Alchemy assumes use of the -c2 and -b options when writing them. Examples Convert the image scan.pcx to a First Publisher ART file: alchemy scan.pcx --F 50 Image Alchemy Freedom of Press --f Freedom of Press is a PostScript interpreter from Custom Applications that converts PostScript files to raster files. The Freedom of Press format is one of the file types it can create. Syntax --f Extension .fop Creator Custom Applications Limitations Output only. Only CMYK 1 bit per component per pixel supported. Comments Freedom of Press images are actually two files, a data file and an info file. You specify the name of the data file and Alchemy automatically generates the name of the info file. The output file is normally output.001, output.002, etc. Alchemy will strip the first part of the name and replace it with 'info', so if you specified an output filename of output.005 there will be another file created called info.005. If you don't specify an extension, Alchemy will use .fop, so you'll get two files named filename.fop and info.fop. Alchemy will overwrite info files without warning. Related options -C Undercolour removal Example Convert the file image.tga to a Freedom of Press image called output.003 and info.003, controlling the undercolour removal process using sample.ucr, scaling the image to 2500 pixels across (and scaling proportionately vertically) using nearest neighbor scaling, and conserving memory: alchemy --f -Csample.ucr -X2500 -+ -$ image.tga output.003 Image Alchemy 51 GEM VDI Image File --g VDI files are files that were developed by Digital Research to use with GEM. Syntax --g Extension .img Creator Digital Research Inc. Used by GEM Variations Reads 1-8 bit grayscale and 3 and 4 bit colour files. Writes 1, 3, and 4 bit grayscale and 3 and 4 bit colour files. Limitations The support for colour and multiple bit grayscale GEM files is not very universal. Therefore make sure the application you are using to read the GEM files can in fact handle them. Alchemy defaults to writing out a 1 bit, black and white GEM file. You can explicitly force a 3 plane colour file by use of the -c8 option and a 4 plane colour file by use of the -c16 option (you may add a -b to write a grayscale file instead of a colour file). Comments Because colour GEM files have only 3 or 4 bits of information and no palette support the quality is generally not very good for scanned images. The GEM format seems to have been designed for line drawings. Examples Convert the image scan.pcx to a black and white GEM file: alchemy scan.pcx --g Convert the image bigscan.tga to a 640x480, 8 colour GEM file, using nearest neighbor scaling and type 2 dithering: 52 Image Alchemy alchemy -c 8 --g bigscan.tga -X640 -Y480 -d2 Do the same thing but write an 8 shade grayscale file with no dithering: alchemy -c 8 --g bigscan.tga -X640 -Y480 -d -b Image Alchemy 53 GIF -g GIF files were originally developed by CompuServe as a machine independent image file format. GIF files are clearly the most popular way of storing 8 bit, scanned or digitized images. In addition the compression ratio achieved by GIF files is usually better than any other 8 bit format in common use. GIF89A files were introduced in 1990 as a method for including text and simple animations. Syntax -g version Parameter version: 0: GIF87A 1: GIF89A The default is GIF87A. Extension .gif Creator CompuServe, Incorporated Used by CompuServe Everyone Variations Reads 1 through 8 bit GIF87A and GIF89A interleaved and non-interleaved files. Writes 1 through 8 bit GIF87A and GIF89A non- interleaved files. Limitations When reading GIF89A files only the first image in the file is read. Any text, overlays, pauses, palette changes, etc. are ignored. Because GIF files only store the size of the palette to the nearest power of 2 the exact palette size is lost when converting to and from GIF files. For example, if you convert a 240 colour Sun Raster file to a GIF file and back to a Sun Raster file the resulting Sun Raster file will have 256 colours. 54 Image Alchemy Comments When writing a file you probably want to use the GIF87A variation, since the GIF89A extensions aren't necessary to store single images and a lot of other software still can't read GIF89A images. The only advantage to GIF89A is that the aspect ratio of the image is preserved (GIF87A does not have a provision for storing aspect ratio). The GIF format includes a field for storing the colour to be used for the background when viewing files. Alchemy does not make use of this value. Alchemy sets the background colour to the darkest colour in the palette when viewing files and organizes the palette such that the first colour is the darkest colour when writing GIF files, if the palette is created by Alchemy (you can override this by using the -z option). Related options -z Palette Selection Examples Convert the image test.pcx to a GIF87A image. alchemy test.pcx -g Convert the file input.tga to a 16 colour GIF89A file: alchemy input.tga -c16 -g1 Image Alchemy 55 GOES --G GOES files are used for satellite image data. Syntax --G goesType Parameter goesType: 0:GARS format 1:McIDAS format The default is 0 (GARS format). Extension .goe Creators The University of Wisconsin National Oceanic and Atmospheric Administration (NOAA) National Environmental Satellite Data Information Service (NESDIS) Used by Various satellite image processing software, including the McIDAS system. Variations Reads 8, 16, and 32 bits per pixel GOES images. Writes 8 bits per pixel images. Limitations When reading 16 and 32 bit images Alchemy discards all but the top 8 bits of data. Alchemy discards any calibration data and level maps when reading images. Because of difficulty in getting a sufficient number of test images in the GOES format (especially the PUT format) reading GOES images has not been thoroughly tested. If you have any GOES images which Alchemy does not read correctly please contact us. Comments The GARS format is a 7680 bytes per block, Motorola byte-order, EBCDIC format; the MCIDAS format is a continuous data, Intel byte-order, ASCII format. Since GOES images are always grayscale, Alchemy assumes the use of the -b and -8 options when writing a GOES file. 56 Image Alchemy GOES images contain a lot of information which is not part of the image data. This information includes the time and date the image was captured, the satellite which captured the image, the type of instrumentation used, etc. When reading a GOES image this information is discarded; when writing a GOES image 0 is written for all values for which data is unavailable. Examples Convert the Erdas file, florida.gis, into a GOES GARS image: alchemy --G0 florida.gis Do the same thing, but write out a GOES McIDAS image: alchemy --G1 florida.gis Image Alchemy 57 Hitachi Raster Format --h Hitachi Raster Format (HRF) files are black and white images used by CADCore. Syntax --h Extension .hrf Creator Hitachi Software Engineering Co., Ltd. Used by Information and Graphics Systems, Inc. (IGS) Comments Since HRF files are always black and white, Alchemy assumes the use of the -b, -8, and -c2 options when writing HRF files. Example Convert the TIFF file page1.tif to a HRF file: alchemy page1.tif --h 58 Image Alchemy HP Printer Command Language (PCL) -P HP PCL files are used by HP LaserJets and compatible printers. Syntax -P compressionType Parameter compressionType: 0: Uncompressed 1: RLE compressed 2: TIFF compressed 3: Delta Row compressed 10:Landscape, Uncompressed 11:Landscape, RLE compressed 12:Landscape, TIFF compressed 13:Landscape, Delta Row compressed 100:LaserJet 4, Uncompressed 101:LaserJet 4, RLE compressed 102:LaserJet 4, TIFF compressed 103:LaserJet 4, Delta Row compressed 110:LaserJet 4, Landscape, Uncompressed 111:LaserJet 4, Landscape, RLE compressed 112:LaserJet 4, Landscape, TIFF compressed 113:LaserJet 4, Landscape, Delta Row compressed The default is uncompressed. Extension .pcl Creator Hewlett-Packard Company Used by HP LaserJet printers HP compatible laser printers Variations PCL files are always 1 bit per pixel, black and white. Reads and writes uncompressed, RLE compressed, TIFF compressed, and Delta Row Compressed files. Reads and writes portrait and landscape files. Image Alchemy 59 Limitations In addition to raster images, PCL files can include text and vector graphics information. When reading Alchemy only pays attention to raster images in the file and attempts to skip everything else. See Appendix A, Answers to Frequently Asked Questions, for further discussion of this. The only resolutions allowed in PCL files are 75 DPI, 100 DPI, 150 DPI, and 300 DPI (and, in the case of LaserJet 4 type files, 200 DPI, and 600 DPI ) The X and Y resolution must be the same. If you specify a non-allowable resolution Alchemy automatically alters the resolution to the next higher resolution. For example, if you specify 250 DPI Alchemy will write a 300 DPI PCL file If no resolution is specified either on the command line or in the input file Alchemy automatically choses the smallest resolution which will allow the entire image to fit on the page. Comments Since PCL files are always 1 bit, black and white files, Alchemy assumes the use of the -b, -c2, and -8 options. When converting colour or gray-scale images to PCL you will probably want to scale the output so the image will be larger than the input image. This will allow the dithering to preserve more detail in the image. PCL files can be used to generate output which can be printed on HP LaserJet and compatible printers. The easiest method is to simply generate a .PCL file and then copy it to the printer by using the copy command (when using the copy command from MS- DOS you will have to use a /B to make sure the entire file is copied to the printer; see the example below for more information). 60 Image Alchemy Not all PCL compatible printers can print all types of compressed PCL file. Specifically, LaserJet II, IID, and earlier printers can print only uncompressed PCL files. LaserJet IIp printers can print only uncompressed and RLE compressed files. LaserJet III, IIID, IIIp, IIIsi, and 4 printers can print all types of compressed PCL files. In general, the higher the compression type, the better the compression ratio. The Landscape option can be used to write a landscape PCL file. Because of changes in the PCL format, only LaserJet III and newer printers can print Alchemy produced landscape PCL files. It is now possible to write a PCL file directly to a HP LaserJet or compatible printer. If you use the name of the device as the output file name Alchemy will redirect output to that device (for example, use prn: as the output file name if your LaserJet is attached to the prn: port) . Examples Convert the image image.gif to a HP PCL file, using no compression: alchemy image.gif -P Convert the image small.gif to a HP PCL file called out.pcl with dimensions of 2000 by 2000 at 300 DPI: alchemy small.gif -P -X2000 -Y2000 -D 300 300 out Print the image generated by the previous example (for MS-DOS machines only). The /B is necessary to tell the copy command that the file is a binary file: copy /B out.pcl prn: Convert the image small.gif to a HP PCL file called out2.pcl with dimensions of 2000 by 2000 at 300 DPI, using TIFF compression: alchemy small.gif -P2 -X2000 -Y2000 -D 300 300 out2 Image Alchemy 61 To print the print the image madonna.gif directly to your Laserjet 4 at the largest resolution, using Delta Row compression with dithering type 22: alchemy madonna.gif -P104 -D600 600 -Xb4800 - YB6600 -+ -d22 prn: To print the print all the TIFF files in the current directory directly to a LaserJet 2: alchemy *.tif -P prn: 62 Image Alchemy HP Raster Transfer Language (RTL) --r RTL files are used by HP colour raster printers and plotters. Syntax --r type Parameter type: 0: PaintJet 1: HP7600 uncompressed 2: HP7600 PackBits compression 3: HP7600 planar uncompressed 4: HP7600 planar PackBits compression 5: HP7600 planar Group III compression 6: on the fly uncompressed 7: on the fly rle 10: NovaJet The default is HP7600 PackBits compression. Extension .rtl Creator Hewlett-Packard Company Used by HP raster plotters and printers including PaintJets and HP 7600 Series plotters. Variations CMYK, 1 bit per component per pixel. Blake and white, 1 bit per pixel. Limitations Output only. Image Alchemy 63 Comments Compression types 6 and 7 are equivalent to types 1 and 2 except they tell the plotter it may plot the data as received instead of waiting for the entire image. This is useful on the DesignJet plotters which have small buffers compared to the imageable area. The NovaJet option cause Alchemy to create RTL files which are compatible with NovaJet plotters. Alchemy will generate a colour RTL file unless the input file is black and white or grayscale or the -b option is specified as part of the conversion. RTL files can be used to produce output which can be printed on HP colour printers and raster plotters. The file can be printed by sending the file to the plotter. There is no additional setup required for the PaintJet. HP7600 series plotters should be in HP-GL/2 mode best results will generally be achieved with compensation off. To get colour plots from the HP7600 series the plotter must be in 4 or 5 pass mode. The file must be sent to the printer/plotter in binary mode (for MS-DOS systems, use the /B option with the copy command). If the input is black and white, you probably want to do the conversion without an undercolour removal file and with dithering off. See below for an example. If the input is gray-scale, you probably do want to use an undercolour removal file to perform density correction, but with 100% black removal (the black removal tables should contain 0 through 255, increasing by one each line) so that the output won't contain cyan, magenta, or yellow. The sample directory on the distribution diskette has a UCR file called gray.ucr which has 100% black removal. Related options -C Undercolour Removal File -d Specify dither type Examples Convert the black and white image test.wpg to a RTL file for a PaintJet called test.rtl, not using a UCR file and with dithering off: alchemy --r0 -d0 test.wpg 64 Image Alchemy Convert the file image.tga to a RTL file for a PaintJet called image.rtl, using the undercolour removal file sample.ucr: alchemy --r0 -Csample.ucr image.tga Convert the file image.tga to a planar RTL file called image.rtl using PackBits compression, controlling the undercolour removal process using sample.ucr, scaling the image to 3000 pixels across using good quality scaling, preserving the aspect ratio (by proportionately scaling the image vertically), and conserving memory: alchemy --r4 -Csample.ucr -Xb3000 -+ -$ image.tga Plot the image generated by the previous example (for MS-DOS machines with the plotter connected to a port which is mapped to prn:): copy /b image.rtl prn: Image Alchemy 65 HP-48sx Graphic Object (GROB) --H Graphic Object files are used by HP-48sx calculators. Syntax --H type Parameter type: 0: Binary 1: ASCII The default is Binary. Extension .grb .asc Creator Hewlett-Packard Company Used by HP -48sx calculators. Variations Black and white, 1 bit per pixel. Examples Convert the image madonna.gif to a ASCII HP-48sx GROB file alchemy madonna.gif --H 1 66 Image Alchemy HSI JPEG --j The HSI JPEG format is a variation of the JPEG format that was designed by Handmade Software to better compress paletted images. Paletted images often have large areas where the image consists of 1 or 2 colours; JPEG compression does a poor job on these sections when compared to LZW compression. HSI JPEG files are a combination of JPEG and LZW compression. Syntax --j Extension .jpg Creator Handmade Software, Inc. Used by Image Alchemy GIF2JPG (another Handmade Software product) Variations 8 bit paletted Comments HSI JPEG files are not compatible with JPEG or JFIF files. If you intend to transfer files to other systems do not use this format, use the standard JPEG format instead (using the -j option). Example Convert the file madonna.gif to a HSI JPEG file: alchemy --j madonna.gif Image Alchemy 67 HSI Palette -l PAL files are palettes which are ASCII files that can be edited with a text editor. Syntax -l (lower case L) Extension .pal Creator Handmade Software, Inc. Used by Image Alchemy Variations Palette files are always ASCII files. Limitations .PAL files contain only a palette. Comments The format of PAL files is described in Appendix H. Related options -f Match image to specified palette -F False colour with specified palette Examples Extract the palette from the GIF file madonna.gif: alchemy madonna.gif -l Convert the file image.tga to a GIF file, matching the palette found in standard.pal: alchemy image.tga -g -f standard.pal 68 Image Alchemy HSI Raw -r HSI Raw files are used internally by Image Alchemy when converting between certain combinations of image formats. If you are interested in converting custom format images to be used with Image Alchemy we suggest using HSI Raw Files. Syntax -r Extension .raw Creator Handmade Software Inc. Used by Image Alchemy Variations 8 bit paletted and 24 bit true colour, uncompressed, not packed. Comments This format is used internally as temporary files by Alchemy when doing certain image conversions; it can also be explicitly read and written. This format is described in Appendix F. Examples Convert the file test.lbm to a raw file: alchemy test.lbm -r Convert the raw file, test.raw, to a 24 bit Targa file called output.tga: alchemy -24 -a test.raw output.tga Image Alchemy 69 IBM Picture Maker --i IBM Picture Maker files are used by IBM presentation software. Syntax --i Extension .pic Creator IBM Used by IBM Storyboard Live! Variations Reads and writes 256 colour Picture Maker files. Limitations 16 colour Picture Maker files are not supported. Picture Maker images cannot be larger than 640x480. Comments This is not the same format as Cubicomp PictureMaker. 256 colour Picture Maker files may be either 320x200 or 640x480. Image Alchemy will write the smallest variation that the image will fit in, with the image centered; the borders will be filled with colour 0. Examples Convert the PCX file, giraffe.pcx, into an IBM Picture Maker file: alchemy --i giraffe.pcx 70 Image Alchemy IFF/ILBM -i IFF (Interchange File Format) files are used by Amiga computers for storing a number of types of data, including images, text, and music; ILBM (InterLeaved BitMap) is a type of IFF file used to store images. Syntax -i Extensions .lbm .iff .ilbm Creator Commodore-Amiga Corp. Used by Amiga Deluxe Paint Variations Reads 1 through 8 bit, 24 bit, HAM, and PBM images Writes 1 through 8 bit and 24 bit images. Limitations Dynamic Hi-Res images are not supported. Does not write images in any of the Amiga specific display modes. Comments If you're writing an ILBM file for use on an Amiga, you probably want to write either a paletted file with 32 colours or a 24 bit file. 24 bit ILBM files can then be converted to one of the Amiga specific display modes with various third-party utilities. Example Convert the file input.pcx to an IFF/ILBM file called output.lbm with 32 colours: alchemy -i -c32 input.pcx output.lbm Image Alchemy 71 Img Software Set --Q The Img Software Set is a collection of tools for manipulating graphic images freely available for various UNIX workstations (see Appendix J for information on how to get a copy of the Img Software Set). Syntax --Q Extensions .img .p .a Creator Paul Raveling Used by Img Software Set Variations Reads and writes 8 bit paletted and 24 bit images. Limitations Alchemy does not read nor write compressed (.Z) images. Use the UNIX supplied uncompress program to decompress those images before reading with Alchemy. Example Convert the Sun Raster file test.ras to an Img Software Set file: alchemy test.ras --Q 72 Image Alchemy JPEG/JFIF -j JPEG is a new type of image file format that uses a lossy compression technique to achieve high compression ratios. See Appendix C, JPEG Compression, for more information. Syntax -j[coding] quality Parameters coding: Specify the type of entropy coding to perform. none: default Huffman coding a: arithmetic coding h: optimum Huffman coding quality: 1 through 100 (larger is higher quality) The default quality is 32. Extension .jpg Creator Joint Photographic Experts Group (JPEG) Used by Lossy compression of photographic images. Variations Gray-scale images are saved as single channel JPEG files; colour images are saved as three channel JPEG files. Reads and writes baseline JPEG with CCIR-601 YCbCr colour space, interleaved components, Huffman or arithmetic coded. Alchemy can read files with any component sub- sampling up to 4x4; it always writes 2h:1v 1h:1v 1h:1v. Alchemy Huffman coded JPEG files comply with the industry standard `JFIF' interchange format. Limitations JPEG files are always lossy, which means that the compressed image is not identical to the original image. At high quality factors (32 and above) this loss is generally so slight as to be barely noticeable. There is no quality factor which is guaranteed to be lossless. Image Alchemy 73 Comments By default, Image Alchemy uses a fixed set of Huffman tables to compress an image. If the -j is immediately followed by an 'h', Alchemy will generate a set of custom tables optimized for the image and quality factor. This usually produces 5-20% better compression (depending on the image content and quality factor) but requires an additional pass over the image data, so it takes a little longer to compress (there's no effect on the decompression time). Alchemy can also use arithmetic coding (by specifying an 'a' after the -j); this will produce 10-20% better compression; this is at the expense of JFIF compatibility and it takes a little longer to both compress and decompress than Huffman coded files. Quality may vary between 1 and 100; the default is 32. The higher the number the higher the quality of the image and the lower the compression ratio. Quality factors below 10 will produce images with significant loss of quality. JPEG files are based on the Joint Photographic Experts Group (JPEG) CD 10918-1 draft standard. Since JPEG compression was designed for use with continuous tone images (such as those produced by a scanner or digitizer), poor results can be expected when compressing line drawings. Related options -q Apply Smoothing when decompressing a JPEG image. Because JPEG compression works on 8x8 pixel blocks there may be discontinuities at the edges of these blocks producing block artifacts. Smoothing attempts to reduce these artifacts. Smoothing is really only necessary at very low quality settings (less than 10); even then the effects of smoothing are not particularly significant. Examples Convert the file photo.tga to a JPEG file called photo.jpg, using a high quality setting: alchemy -j70 photo.tga Convert the file photo.tga to a JPEG file called photo.jpg, using a low quality setting and generating optimum Huffman tables: alchemy -jh10 photo.tga 74 Image Alchemy Convert the JPEG file, lores.jpg, to a PCX file using smoothing: alchemy lores.jpg -p -q Image Alchemy 75 Jovian VI --J Jovian VI files are created by the Jovian Logic video capture boards. Syntax --J Extensions .vi Creator Jovian Logic Corp. Used by Jovian Logic Variations Reads 1, 4, 6, and 8 bit gray-scale images, 4 and 8 bit colour paletted images, and 16 and 24 bit true colour images. Writes 8 bit gray-scale, 4 and 8 bit colour paletted images, and 16 and 24 bit true colour images. Limitations Reads files with 6 and 8 bit palettes, always writes 6 bit palettes. Gray-scale files are always 8 bit. Comments When writing a VI file the palette always starts at 0, but will not necessarily be black (which is the way that Jovian VI files are written). Example Convert the GIF file, test.gif, to a 16 colour VI file: alchemy test.gif --J -c16 76 Image Alchemy Lumena CEL --L Lumena CEL files are used by Time Arts software. Syntax --L Extension .cel Creator Time Arts Used by Lumena Variations Reads and writes 15 and 32 bit images. Limitations The Alpha channel in 32 bit images is ignored. Example Convert the file test.tga to a Lumena CEL file: alchemy --L test.tga Image Alchemy 77 Macintosh PICT/PICT2 -m PICT files were created by Apple Computer as a common format for Macintosh applications to use. Virtually every Macintosh application can use PICT files. Syntax -m macBinary Parameters macBinary: 0:do not write a MacBinary file 1:write a MacBinary file The default is to not write a MacBinary file. Extensions .pict .pic Creator Apple Computer, Inc. Used by Macintosh computers Variations Reads 1, 2, 4, 8, 16, and 32 bit PICT and PICT2 images Writes 1, 2, 4, 8, and 32 bit PICT2 images. Limitations Only pays attention to pixMaps in the image; attempts to skip everything else. Comments Due to the enormous number of options allowed in PICT files, reading PICTs may not always work. See Appendix A, Answers to Frequently Asked Questions, for more information. Adding a MacBinary header to a MacPaint file is useful if transfering the file to a Macintosh computer over by modem. The MacBinary header will allow the Macintosh to automatically recognize the file as a MacPaint file. Example Convert the file input1.gif to a Mac PICT file called input1.pic: alchemy -m input1.gif 78 Image Alchemy MacPaint --t MacPaint files are black and white images used by Macintosh computers. Syntax --tmacBinary Parameters macBinary: 0:do not write a MacBinary file 1:write a MacBinary file The default is to not write a MacBinary file. Extensions .mac Creator Apple Computer, Inc. Used by Macintosh computers Variations 1 bit, black and white. Limitations MacPaint images are always 576x720 pixels. If you attempt to write a MacPaint image which is larger, Alchemy will report this as an error. If you write an image which is smaller Alchemy will pad the image with white space along the right-hand side and bottom. Because MacPaint images are always black and white, the -c2, -8, and -b options are assumed when writing an image. Comments Adding a MacBinary header to a MacPaint file is useful if transfering the file to a Macintosh computer over by modem. The MacBinary header will allow the Macintosh to automatically recognize the file as a MacPaint file. Example Convert the file input1.gif to a MacPaint file called input1.pic: alchemy --t input1.gif Image Alchemy 79 MTV Ray Tracer --M MTV files are used by the MTV RayTracer, a public domain ray tracer for Suns and other workstations. Syntax --M Extension .mtv Creator Mark T. VandeWettering Used by MTV Raytracer Variations 24 bit true colour. Comments MTV is a public domain ray-tracer available free of charge via anonymous ftp from drizzle.cs.uoregon.edu or via floppy disk from us. Example Convert the file spheres.img to a MTV file: alchemy spheres.img --M 80 Image Alchemy Multi-Image Palette -L This option will generate an optimum palette for a variable number of images. This is useful for finding a common palette where multiple images are used (animations, for instance), without resorting to a uniform palette. Syntax -L filename Parameters filename is the name of the palette file which will contain the optimized palette for all of the images. Extension .pal Creator Handmade Software, Inc. Used by Image Alchemy Variations Palette files are always ASCII files. Limitations .PAL files contain only a palette. Comments The format of PAL files is described in Appendix H. Related options -f Match image to specified palette -F False colour with specified palette Examples Generate an optimum palette for all GIF files in the current directory: alchemy *.gif -L Image Alchemy 81 OS/2 Bitmap (BMP) -O OS/2 BMP files are used by IBM OS/2 2.0. Syntax -O compressionType (Uppercase letter o) Parameter compressionType: 0:None 1:RLE The default is none. Extension .bmp Creator IBM Corp. Used by OS/2 2.0 Variations Reads 1, 4, 8, and 24 bit RGB (raw), RLE4, and RLE8 files. Writes 1, 4, 8, and 24 bit RGB (raw), RLE4, and RLE8 files. Comments Examples Convert the image test.jpg to a OS/2 BMP file: alchemy test.jpg -O 82 Image Alchemy PCPAINT/Pictor Page Format -A The Pictor format was designed so that an image could be loaded into an IBM graphics adapter very quickly; it does this by almost exactly duplicating the organization of the graphics adapter memory. This makes the format hardware dependent. Syntax -A type Parameter type: 0:320x200x4 CGA* 1:320x200x16 PCjr/Tandy* 2:640x200x2 CGA* 3:640x200x16 EGA 4:640x350x2 EGA 5:640x350x4 EGA 6:640x350x16 EGA 7:720x348x2 Hercules* 8:640x350x16 VGA 9:320x200x16 EGA 10:640x400x2 AT&T/Toshiba* 11:320x200x256 VGA/MCGA 12:640x480x16 VGA 13:720x348x16 Hercules InColor* 14:640x480x2 VGA/MCGA 15:800x600x2 EGA/VGA 16:800x600x16 EGA/VGA 17:640x400x256 SVGA 18:640x480x256 SVGA 19:800x600x256 SVGA 20:1024x768x2 SVGA 21:1024x768x16 SVGA 22:360x480x256 VGA 23:1024x768x256 SVGA The default is 640x480x256 SVGA. *These modes are not yet supported. Extension .pic .clp Creator John Bridges Used by PCPAINT GRASP Image Alchemy 83 Variations There are variations for most IBM and third party graphics adapter display modes. Limitations Only the EGA and VGA modes are supported at this time. Text modes are not supported. Comments Some Pictor files do not contain palettes. For those files Alchemy will default to using a standard palette appropriate to the display mode the file was saved in. However, the image may not use the default palette; in that case you can read the palette from another file with the -F false colour option. Related options -F False colour Example Convert the file image.pcx to a Pictor file called image.pic, for 800x600x256 SVGA mode: alchemy -A19 image.pcx 84 Image Alchemy PCX -p PCX files are used extensively by MS-DOS machines. Originally created by ZSoft for use by their paint packages, PCX files can be read and written by almost all MS-DOS paint software and desktop publishing software. A new variation of PCX file, DCX, is used by many MS-DOS fax boards. PCX files suffer from two problems: the compression ratio is poor for 8 and 24 bit images and PCX files are often written out incorrectly; see the Limitations section below for details. Syntax -p type Parameter type: 0:Standard PCX 1:DCX 2:PCJ The default is standard PCX. Extension .pcx Creator ZSoft Corporation Used by PC Paint Publisher's Paintbrush Most paint and desktop publishing software can read and write PCX files. Fax board software uses the DCX variation of PCX. Variations 1, 4, 8, and 24 bits per pixel for standard PCX files. 1 bit per pixel for DCX files. 8 bits per pixel for PCJ files. Limitations PCX format files are often written out incorrectly; Alchemy attempts to figure out what is wrong and make intelligent decisions (things Alchemy can deal with include PCX files without palettes, files missing the last line of image data, and files with illegal (and incorrect) combinations of bits per pixel and planes). Image Alchemy 85 24 bit PCX files are very new and most other software cannot read them. Therefore, unless you are sure that the software you are using can read a 24 bit PCX file, you probably want to use the -8 option to force Alchemy to write a paletted file when generating a PCX file. DCX files are multiple page PCX images which are used by various manufacturers of fax boards and fax software. Alchemy only reads the first page of a DCX file. Alchemy always writes single page DCX files which are black and white. Comments Because so many software packages can read and write PCX files we are especially interested in supporting as many variations as possible. If you have any PCX files which Alchemy does not read correctly please contact us. Since DCX files are always 1 bit, black and white images, Alchemy assumes the use of -b -c2 -8 when writing the DCX variation of PCX. ZSoft recently changed some of the information in the header of PCX files so they now include image resolution. Some fax board software makes use of this information when transmitting PCX or DCX files as faxes. See the example section below for an example of how to specify image resolution when writing a PCX file. PCJ files are a variation of 256 colour PCX files which have the palette in a separate file. The palette file has the extension .p13. Alchemy will automatically look for the palette file in the same directory as the PCJ file when reading. Related options -D Specify image resolution. Example Convert the GIF file, lush.gif, to a PCX file: alchemy lush.gif -p Convert the scanned image, page1.tif, to a DCX file: alchemy -p1 page1.tif 86 Image Alchemy Convert the scanned image, page2.tif, to a DCX file, specifying an image resolution of 200x100 (a common resolution for fax images): alchemy -p1 page2.tif -D 200 100 Image Alchemy 87 PDS --p PDS labeled images are used by NASA for planetary images. Syntax --p Extensions .ibg .imq Creator NASA Used by NASA distributes collections of planetary images on CD-ROM in PDS format. Variations Reads 1 and 8 bit uncompressed and 8 bit first difference Huffman compressed files. Writes 8 bit gray-scale uncompressed PDS files. Limitations PDS images must begin with either an "SFDU_LABEL" or a "FILE_TYPE" record for Alchemy to be able to identify it. Occasionally a PDS labeled image has a palette. There doesn't seem to be any standard format for the palette; Image Alchemy handles the palettes we've encountered. Any portions of the PDS labels not required to extract the image, such as longitude and latitude, are ignored. Comments Since Image Alchemy only writes gray-scale PDS images, Alchemy assumes the use of the -b option when writing PDS files. Some PDS images actually consist of two files, a label file and a data file. To read that type image you should use the name of the label file and Alchemy will find the data file. Examples Convert the GOES file, phoenix.goe, into a PDS labeled image: alchemy --p phoenix.goe 88 Image Alchemy Portable BitMap (PBM) -k The Portable BitMap format was developed by Jef Poskanzer to allow the transferring of black and white image files between different workstations. The PBM format has grown to include black and white, gray-scale, and true colour images, a large set of programs to convert various other image formats to and from PBM, and a set of image manipulation tools. The PBM tools are available free of charge (unfortunately, due to their memory requirements, many are not useable on MS-DOS machines). Syntax -k Extensions .pnm Portable aNyMap (Any of those below) .pbm Portable BitMap (Black and white) .pgm Portable GrayMap (Gray-scale) .ppm Portable PixelMap (True colour) Creator Jef Poskanzer Used by Portable BitMap Package Various workstation graphic programs Variations Reads and writes 1, 8, and 24 bit RAWBITS (binary) images. To write out a PBM file use -b -c2. To write out a PGM file use -b -c256. To write out a PPM file use -24. Limitations When writing a PBM file Alchemy always uses the .pnm extension (the extension should be changed based on the type of file being written). Comments The PBM package is a set of image manipulation tools which run on various workstations. The software is available for free via anonymous ftp from expo.lcs.mit.edu as contrib/pbmplus.tar.Z, ftp.ee.lbl.gov as pbmplus.tar.Z, or via floppy disk from us. Examples Convert the file sun.im32 to a PBM file: alchemy sun.im32 -k -b -c2 Convert the file sun.im32 to a PGM file, overwriting any existing sun.pnm file: Image Alchemy 89 alchemy sun.im32 -k -b -c256 -o Convert the file sun.im32 to a PPM file called image77: alchemy sun.im32 -k -24 image77 -. 90 Image Alchemy Puzzle --U The Puzzle format is used by the UNIX supplied Puzzle program Syntax --U Extensions .pzl.puzzle .cm Creator Unknown Used by The puzzle program. Variations 8 bits per pixel Example Convert the file einstein.im8 to a Q0 file: alchemy einstein.im8 --q Image Alchemy 91 Q0 --q The Q0 format is apparently commonly used by various Japanese scanning, painting, and viewing software to store 24 bit images. Handmade Software has no information other than a basic description of the format and some sample images; if you have further information on the Q0 format please contact us. Syntax --q Extensions .q0 For pixel data .rgb For pixel data .fal For image header information Creator Unknown Used by Various Japanese image processing software. Variations 24 bits per pixel Comments Q0 files are actually two files, one with the extension .rgb or .q0 and the other with the extension .fal. The .rgb or .q0 file contains the actual image data and the .fal file contains the header information (primarily the height and width of the image). You specify the name of the .rgb or .q0 file and Alchemy automatically generates the name of the .fal file. When writing a Q0 file Alchemy will overwrite, without warning, existing .fal files. Example Convert the file dogcow.gif to a Q0 file: alchemy dogcow.gif --q 92 Image Alchemy QDV --D The QDV format is used by Giffer, a Macintosh program which displays and converts image files. Syntax --D Extension .qdv Creator Steve Blackstock Used by Giffer Variations QDV files are always 8 bits per pixel. Comments Giffer is a great shareware (Beerwaretm, actually) program for the Macintosh that converts between various image file formats and allows viewing of graphics files. Since QDV files are always paletted, Alchemy assumes the use of the -8 option when writing QDV files. Example Convert the file input.tga to a qdv file: alchemy input.tga --D Image Alchemy 93 QRT --T QRT files are generated by the QRT Ray Tracer, a public domain ray-tracer for Amiga, Macintosh, and IBM PC computers. Syntax --T Extension .raw Creator Steve Korn Used by QRT Ray Tracer Variations 24 bits per pixel Comments Since QRT files are always true colour, Alchemy assumes use of the -24 option. Example Convert the file spheres.gif to a QRT file called spheres.raw: alchemy --T spheres.gif 94 Image Alchemy RIX -R RIX files are colour files developed by ColoRIX to use with their paint software. Syntax -R Extension .scx .rix Creator RIX Softworks, Inc. Used by ColoRIX software Variations Reads and writes Type 0 (8 bits per pixel) and Type 4 (4 bits per pixel) images. Limitations We would like to add support for Type 1 and Type 2 images but we haven't been able to find any; if you have some please contact us. Comments A type 0 file will be written if there are more than 16 colours in the image; otherwise a type 4 file will be written. Examples Convert the file test.gif to a RIX file: alchemy test.gif -R Image Alchemy 95 Scodl --s Scodl files are used by Agfa/Matrix slide recorders. Syntax --s Extension .scd type Parameter type: 0: Non-scalable image (pre MVP version 4.2) 1: Scalable image (MVP version 4.2 or later) The default is 0 (Non-scalable). Creator Agfa Corporation / Matrix Instruments Inc. Used by Agfa/Matrix slide recorders Variations Writes 8 and 24 bit run-length coded (RLC) images. Limitations Output only. Comments Agfa/Matrix made significant changes to the Scodl file format when they introduced version 4.2 of the MVP and Conductor software in 1992. Old version Scodl files could not be scaled by the MVP software; new version Scodl files can be scaled but only work the newer version of the MVP and Conductor software. 96 Image Alchemy Scalable Scodl images have the advantages that they do not have to be scaled to a specific output resolution and are therefore generally smaller than pre-scaled Scodl images. They will can also be imaged on a film recorder with any output resolution or previewed on a monitor. The disadvantage of scalable Scodl images is that you must be using at least Scodl MVP version 4.2 and the Scodl MVP software does not perform very high-quality scaling. In particular, the MVP software only does pixel replication scaling when increasing the size of an image (this corresponds to type 'a' scaling in Alchemy) and pixel averaging when reducing the size of an image (corresponding to Alchemy 'b' scaling). Note that Alchemy pays attention to the aspect ratio or dots per inch information specified as part to command line or present in the original image when converting to a Scodl scalable image. Therefore you should insure that this information is correct when writing a Scodl scalable image. When writing Pre 4.2 Scodl files the image should be scaled up to either 2000x1366 or 4000x2732 to fill the slide. There are some limitations with the current version of the MVP software driver supplied by Agfa/Matrix: 24 bit Scodl files are not correctly interpreted by the MVP driver version 4.1 and earlier. 8 bit images are correctly interpreted. When sending very large images to the background MVP driver you must be using version 4.0 or later and have lots of EMS memory (4 Megabytes is recommended). When using the foreground MVP program turning on disk caching is necessary. Example Convert the file picture.im32 to a Scodl file using high quality scaling and preserving the aspect ratio: alchemy --s -Xc2000 -Yc1366 -+ picture.im32 Image Alchemy 97 Silicon Graphics Image (SGI) -n Silicon Graphics Image files are used by Silicon Graphics workstations. Syntax -n compressionType Parameter compressionType: 0:Verbatim (uncompressed) 1:RLE compressed The default is 0 (Verbatim). Extension .sgi Creator Silicon Graphics, Inc. Used by Silicon Graphics workstations. Variations Reads and writes 1, 8 (gray-scale), and 24 bit verbatim (uncompressed) and RLE files. Comments Only gray-scale images may be 8 bit files. Alchemy will automatically switch to 24 bit mode when writing a colour image. Example Convert the Sun raster file sun.im8 to a SGI file called sgiout: alchemy -n sun.im8 sgiout -. Do the same thing, but write out a RLE compressed SGI file: alchemy -n1 sun.im8 sgiout -. 98 Image Alchemy SPOT Image --S SPOT Image files are high-resolution satellite images produced by SPOT Image Corporation. Syntax --S Extensions For GIS (tape) format: .hdr (For image header information) .bil (For pixel data) .clr (For palette data [optional]) For CCT (CD-ROM) format: .dat Creator SPOT Image Corp. Used by SPOT Image Corp. Variations 8 bits per pixel for GIS (tape) format files 8 and 24 bits per pixel for CCT (CD-ROM) format files Limitations Only GIS (tape) format images are written. Comments SPOT Image GIS (tape) images are actually three files. You specify the name of the .hdr file and Alchemy automatically generates the name of the .bil and .clr files. If no palette file (.clr file) exists Alchemy will assume the image is grayscale. There may also be a statistics file with a .stx extension, but Alchemy ignores this file. When writing a SPOT file Alchemy will overwrite, without warning, existing .bil and .clr files. When reading a CCT (CD-ROM) format image specify the complete path and name of the image file. For example: alchemy l:\scene04\imag_04.dat -g will convert the scene 4 image to a .gif file. Image Alchemy 99 Examples Convert the Erdas file, phoenix.lan, to a SPOT Image file: alchemy --S phoenix.lan 100 Image Alchemy Stork -K Stork files are CMYK images used by Stork's colour proofing machines. Syntax -K compressionType Parameter compressionType: 0:None 1:Run length coded The default is none. Extensions .idx Index file .pre Image data .tab Colour lookup table Creator Stork Colorproofing B.V. Used by Stork Colorproofing machines Variations Reads and writes 32 KCMY, 32 KCMY RLC, 16 CLU, and 16 CLU RLC images (type 100, 101, 300, and 301, respectively). Limitations Alchemy can't write paletted files with more than 256 colours. When reading paletted files with more than 256 colours they are treated as true colour. Comments Stork images are stored in two or three files (depending on whether or not there's a colour lookup table associated with the image). The filename given to Alchemy should be the name of the data file (normally with a suffix of .pre); Alchemy will generate the names of the other files by stripping the extension and appending .idx for the index file and .tab for the colour lookup table (if any). Alchemy will overwrite existing .idx and .tab files without warning when creating Stork files. Related options -C Undercolour Removal File Example Convert the file image.tga to an uncompressed Stork image called image.pre and image.idx, using the undercolour removal file sample.ucr: alchemy -K -Csample.ucr image.tga Image Alchemy 101 Sun Icon --N Sun Icon files are used by Sun Microsystems workstations. Syntax --N Extensions .icon .ico Creator Sun Microsystems, Inc. Used by Sun workstations Variations 1 bit, black and white. Example Convert the sun raster file icon.im1 to a sun icon file called program.ico: alchemy -s icon.im1 program.ico 102 Image Alchemy Sun Raster -s Sun Raster files are used by Sun Microsystems workstations. Syntax -s compressionType Parameter compressionType: 0:None 1:Run length compression The default is None. Extensions .rast .ras .im .im1 .im8 .im24 .im32 Creator Sun Microsystems, Inc. Used by Sun workstations Variations Reads 1, 8, 24, and 32 bit Standard, BGR, RGB, and Byte Encoded (RLE) files. Writes 1, 8, 24, and 32 bit Standard files, and 1 and 8 bit Byte Encoded (RLE) files. Limitations For a short time a version of the PBM toolkit wrote Sun Raster files which had the wrong RGB order. Unfortunately there seem to be many images which were generated with this incorrect RGB order. Please be aware that Alchemy's Sun Raster reading and writing capability has been extensively tested and compared to various other tools; the RGB order we use is correct. Comments Sun Raster files are normally not compressed and so take up lots of disk space. There is no standard extension for Sun Raster files; the extensions that Alchemy uses seem to be the most common. Example Convert the SGI file sgiout to a sun raster file called sun.im8: alchemy -s sgiout sun.im8 Image Alchemy 103 Do the same thing, but write out a compressed sun raster file: alchemy -s1 sgiout sun.im8 104 Image Alchemy Tagged Interchange File Format (TIFF) -t TIFF is designed to be a universal raster image format. It's very popular with desktop publishing packages. Syntax -t compressionType Parameter compressionType: 0:None 1:LZW 2:PackBits 3:Group III Fax 4:Group IV Fax 5:CCITT RLE The default is LZW Compression. Extensions .tiff .tif Creator Aldus Corp. Microsoft Corp. Used by Various desktop publishing and scanning software. Variations Reads TIFF class B, G, R, and most class P files. Reads 1, 4, 8, 12, 24, and 32 bit images (ignoring the alpha channel for 32 bit images). Input compression types supported are raw, LZW, PackBits, Group III fax, Group IV fax, CCITT RLE (byte and word aligned), NeXT, Thunderscan, PICIO, and SGI RLE. Writes class B, G, P, and R files, depending on the input file and options specified. Writes 1, 4, 8, and 24 bit images. Limitations Class P TIFF files can only be read if they have 1, 4, or 8 bits per pixel. Image Alchemy 105 Comments 1,4, and 8 bit output files are paletted unless the palette is all gray, in which case the output is a gray-scale file. If you have TIFF files with 3, 5, 6, or 7 bits per pixel please contact us. When writing TIFF files using any of the fax compression types (Group III, Group IV and CCITT RLE), Alchemy uses a photometric interpretation of minIsWhite. Example Convert the file input.gif to an uncompressed gray-scale TIFF file called output.tif: alchemy -t0 -b input.gif output.tif 106 Image Alchemy Targa -a Targa files were created to support the line of Targa graphics cards. The Targa format is popular with scanners and high end paint packages. Syntax -a outputType Parameter outputType: 0:uncompressed 1:Run Length Coded 10:uncompressed, no footer 11:Run Length Coded, no footer The default is 0 (uncompressed). Extension .tga Creator Truevision, Inc. Used by Various scanning and paint software. Variations Reads 8, 15, 16, 24, and 32 bit images, ignoring the alpha channel for 32 bit images. Writes 8, 15, 16, 24, and 32 bit images, writing an empty alpha channel for 32 bit images. Comments 15 and 16 bit output are actually the same except for one field in the header. Targa files allow a footer containing additional information such as aspect ratio. However some software is unable to read Targa files which have a footer, so Alchemy allows all valid combinations to be written. The most common variant for software to be able to read is 24 bit uncompressed (specify -a0 and -24). Example Convert the file input.tif to an uncompressed 24 bit Targa file: alchemy input.tif -a -24 Convert the file input.tif to an uncompressed 15 bit Targa file called output.tga with no footer: alchemy -a10 -15 input.tif output.tga Image Alchemy 107 Utah Raster Toolkit (RLE) --u The Utah Raster Toolkit is a set of public domain utilities for manipulating and converting images for various workstations. The source code is freely available (see below). Syntax --u Extension .rle Creator The University of Utah The University of Michigan Used by Utah RLE toolkit Variations Reads and writes 1 and 3 channel 8 bits per pixel files; the Alpha Channel is ignored during reading. Limitations While reading, files which are 1 channel and have either no colour map or a single channel colour map are assumed to be gray-scale images. The colour map, if present, will be used as a gamma correction table. Files which are 1 channel and have a 3 channel colour map are assumed to be paletted colour files. Files which are 3 channel are assumed to be true colour. When writing RLE files Alchemy will generate a 1 channel file with a 3 channel colour map for paletted images and a 3 channel file with no colour map for true colour images. Comments The Utah Raster Toolkit is available free of charge as pub/urt-3.0.tar.Z via anonymous ftp from cs.utah.edu, weedeater.math.yale.edu, or freebie.engin.umich.edu or via floppy disk from us. Example Convert the PBM file, image.ppm, to a Utah RLE file: alchemy image.ppm --U 108 Image Alchemy Vivid --I Vivid is a shareware ray-tracer for MS-DOS computers. Syntax --I (upper case i) Extension .img Creator Steven B. Coy Used by Vivid Ray Tracer Variations Reads and writes 24 bit RLE files. Comments The Vivid Ray Tracer is a shareware program for PCs and is available from Stephen Coy 15205 NE 13th Pl., #2904 Bellevue, WA 98007 Example Convert the file spheres.qrt to a Vivid file: alchemy spheres.qrt --I Image Alchemy 109 Windows Bitmap (BMP) -w Windows BMP files are used by Microsoft Windows. Syntax -w compressionType Parameter compressionType: 0:None 1:RLE 10:Write an ICOn file The default is none. Extension .bmp Creator Microsoft Corp. Used by Microsoft Windows Variations Reads 1, 4, 8, and 24 bit RGB (raw), RLE4, and RLE8 files. Writes 1, 4, 8, and 24 bit RGB (raw), RLE4, and RLE8 files. Limitations Several of the programs which claim to read and write RLE files do not do so correctly; we do not recommend writing RLE files unless you have verified that they work with your intended application. Comments Microsoft supplied Windows utilities cannot read nor write RLE4 or RLE8 files. If you are converting an image to use as wallpaper on a 16 colour display you will want to match the palette of the output image to one of the existing 16 colour BMP images supplied with Windows (chess.bmp, for example). If you do not do this the wallpaper will not be loaded correctly. See the example section below. If you are converting an image to use as wallpaper on a 256 colour Windows 3.1 display you will want to reserve the first 8 colours. Use the -c 256 8 option to do this (see below for an example). This will force the first 8 colours of the palette to be the standard Windows colours. 110 Image Alchemy If you are writing a Windows icon (.ico) file you must scale the image to a width and a height of 16, 32, or 64 pixels (32 being the best choice, since Windows displays all icons as 32x32). Also, Windows seems to remap all icons to the standard 16 colours, so the best results can be obtained if you match the palette of your icons to an existing icon (see the -f option). If you don't have any other icons you can also match to one of the 16 colour wallpaper files supplied with Windows. Alchemy can write a BMP file which contains an identity palette as specified in the Microsoft Multimedia Development Kit. These images provide for quicker bitmap loading when used with the Multimedia Extensions. A palette identity file has the first and last 10 palette entries reserved for 20 system defined colours. Alchemy will write such an image if you specify -c 246 10 as part of the command line. Note that ordinarily this would produce a file which has 246 palette entries, but in this special case the file will have 256 palette entries (20 fixed by the Windows specifications and 236 chosen by Alchemy). Note that you can also specify a number smaller than 246, but the palette will always have 256 colours (since the last 10 have to occupy positions 246 through 255). Related options -c Specify number of colours -f Match to existing palette Examples Convert the image test.gif to a Windows BMP file: alchemy test.gif -w Convert the image test.gif to a 16 colour Windows BMP file to be used as wallpaper (the file chess.bmp is supplied with Windows 3.0 (substitute leaves.bmp when using Windows 3.1); this example assumes that it is in the current directory): alchemy test.gif -f chess.bmp -w Convert the image test.gif to a 256 colour Windows BMP file to be used as wallpaper with Windows 3.1: alchemy test.gif -c256 8 -w Convert the image test.gif to an icon file for use with Windows 3.1: Image Alchemy 111 alchemy test.gif -Xb32 -Yb32 -w 10 -f leaves.bmp Convert the image test.gif to an identity palette BMP file: alchemy test.gif -w -c 246 10 112 Image Alchemy WordPerfect Graphic File -W WordPerfect files are images which can be imported into WordPerfect and various other word processors and desktop publishing programs. Syntax -W Extension .wpg Creator WordPerfect Corp. Used by WordPerfect Variations 1 through 8 bits per pixel are supported. Comments In addition to raster images WordPerfect files may contain vectors and text information. Such information is lost when reading WordPerfect files. Example Convert the image, newpict.pcx, to a black and white WPG file: alchemy newpict.pcx -b -c2 -W Image Alchemy 113 XBM --b XBM files are used by the X Windowing System. XBM files are C source code files which can be read and written by various X utilities and are designed to be included in C source code for use as icons and other bit-mapped graphic images. Syntax --b Extensions .xbm .bm Creator MIT Used by The X Windowing system Variations 1 bit per pixel Limitations Because .xbm files are actually C source code files there can be many variations of .xbm files. Since adding a C preprocessor to Alchemy to handle all the theoretically allowable .xbm files is impractical we have instead designed Alchemy to interchange .xbm files with the PBM utilities and the X supplied utilities, and to read the sample .xbm files from Sun Microsystems. If you run across any .xbm files which Alchemy cannot read please contact us. The hotspot field is ignored when reading .xbm files. Comments Most of the X supplied utilities (bitmap, for example) are designed to edit small .xbm images. Example Convert the file picture.im32 to an XBM file using high quality scaling and preserving the aspect ratio: alchemy --b -Xb64 -+ picture.im32 114 Image Alchemy XPM --x XPM files are used by the X Windowing System. XPM files are C source code files which can be read and written by various X utilities and are designed to be included in C source code for use as icons and other bit-mapped graphic images. Syntax --x type Parameter type: 0: XBM similar style 1: XPM3 style 2: XPM2 style The default is XBM similar style. Extensions .xpm .pm Creator MIT Used by The X Windowing system Variations 8 bits per pixel Limitations Because .xpm files are actually C source code files there can be many variations of .xpm files. Since adding a C preprocessor to Alchemy to handle all the theoretically allowable .xpm files is impractical we have instead designed Alchemy to interchange .xpm files with the PBM utilities and the X supplied utilities, and to read the sample .xpm files from IBM. If you run across any .xpm files which Alchemy cannot read please contact us. Some XPM files contain colour names instead of color values for some of the colours. The conversion table of these names into values is in a file supplied with the X Windowing system called rgb.txt. When needed Alchemy will look for this table in the following directories: the current directory, /usr/lib/X11, $OPENWINHOME, and /usr/openwin/lib. If your system has the rgb.txt file in a different location you may have to copy it to the current directory (its location is system dependent; ask you system administrator if you need help finding it). Image Alchemy 115 Comments The different type XPM files can be identified as follows: Type 0: #define type0_format 1 _ static char *type0_colors[] = { "a", "#000000", _ Type 1: /* XPM */ static char * type1[] = { "32 20 12 1", "a c #000000", _ Type 2: ! XPM2 32 20 12 1 a c #000000 _ When writing an XPM file with less than 27 colours Alchemy writes 1 character XPM files, otherwise Alchemy writes 2 character XPM files. XPM files are usually quite small, therefore many utilities (the PBM toolkit for example) may have trouble reading large XPM files. Example Convert the file picture.im32 to an XPM file using high quality scaling and preserving the aspect ratio: alchemy --x -Xb64 -+ picture.im32 116 Image Alchemy XWD --w XWD is the file format used by xwd, the X window dumping utility. Syntax --w type Parameter type: 0: Z type 1: XY type The default is Z type. Extension .xwd Creator MIT Used by The X Windowing System Variations Reads 1, 4, 8, and 24 bits per pixel Z format and 1, 4, and 8 bit XY format XWD files. Writes 1, 8, and 24 bits per pixel Z format and 1 and 8 bit XY format XWD files. Limitations XY format files are not supported. Example Convert the XBM file, icon.xbm, to an XWD file: alchemy icon.xbm --w Image Alchemy 117 5 General Options ------------------------------------------------------------------- Introduction General options are options which do not affect the conversion of the image. They control such things as the overwriting of existing files and the way that memory is used. If you are currently using the Alchemy's menu interface rather than the command-line, you can focus on the purpose, comments, and limitations entries in this chapter. 118 Image Alchemy Conserve Memory -$ Purpose Use as little memory as possible when converting images. Syntax -$ (dollar sign) Comments Normally Alchemy tries to work on chunks of the image several lines long to improve performance. Use of the -$ option will cause it to use the smallest size chunks possible for the conversion being performed. On MS-DOS based systems this will usually allow conversion of larger images than would otherwise be possible. On UNIX systems this may reduce paging when converting very large images. Example Convert the image giant.tga to a 16 colour TIFF file conserving memory: alchemy giant.tga -$ -t -c16 Image Alchemy 119 Display Image Stats -x Purpose Display image statistics. Syntax -x Comments Displays image type, size, number of colours, aspect ratio, resolution, and compression ratio. Limitations Cannot be combined with other options. Example Find out about the image called image.tga: alchemy -x image.tga 120 Image Alchemy Do not alter output filename -. Purpose Disable automatic appending of the output image type to the output file name. Syntax -. (period) Comments By default, if there's no '.' in the output filename, Alchemy will add an extension indicating the type of file. If the -. option is specified no extension will be added. This is most useful on non-MS-DOS systems where '.' is not a special character in filenames. Example Convert the file called infile.gif to a PCX file called outfile (if you did not use the -. option Alchemy would automatically change the output file name to outfile.pcx): alchemy infile.gif outfile -p -. Image Alchemy 121 Help -h Purpose Give you information on how to use Image Alchemy. Syntax -h option Parameter option 0: general help 1: general options 2: output formats a-k 3: output formats l-z 4: colour options 5: scaling options 6: display options (MS-DOS Only) Default is 0, general help Comments The help information given by this command is only a summary. Limitations The help option cannot be combined with any other options. Related options -? support and update information Example Get help on the colour options: alchemy -h4 122 Image Alchemy Overwrite -o Purpose Force Alchemy to overwrite existing files on the disk. Syntax -o Comments Image Alchemy will not overwrite an existing file unless the -o option is specified. Limitations The input file name and the output file name cannot be the same. Example Convert the file input.tga to a GIF file called output.gif, overwriting the existing file called output.gif: alchemy input.tga -g output.gif -o Image Alchemy 123 Program information -? Purpose Give you information on how to get support for Image Alchemy or inquire about update information. Syntax -? Comments Sun-3 and Sun-4 users have to escape the question mark with a back-slash (instead of -? use -\?). This is because the UNIX shell will attempt to perform wildcard expansion on the question mark. Limitations The information option cannot be combined with any other options. Related options -h help with commands Example Get support information: alchemy -? 124 Image Alchemy Quiet -Q Purpose Suppress all status messages (but not error messages). Syntax -Q Comments This is useful when running Alchemy in the background on UNIX systems or in batch files on MS-DOS systems (and you don't want the output of Alchemy scrolling important messages off of the screen). Limitations There is no way to suppress error messages. Example Convert the file dummy.gif to a PCX file but don't report any status messages: alchemy -Q dummy.gif -p Image Alchemy 125 Warnings --W Purpose Treat missing input files, unidentifiable input files, and non-overwriteable output files as a non-fatal errors. Syntax --W Comments When used in conjunction with the Wildcard option (see below) the Warnings option allows Alchemy to proceed even when certain error conditions occur. Specifically, any input files which are missing or can't be identified as valid image files, and any output files which already exist but are not to be overwritten, are skipped and processing continues with the next file. At the end of processing Alchemy displays lists of the files which were not found, which could not be identified, and which already existed but could not be overwritten. This option was added at the request of our customers who routinely convert large numbers of files and don't want Alchemy to stop if it finds a file missing or finds that an output file already exists. Limitations Any errors which occur during the processing of an image file are always fatal. This option can only be used with the Wildcard option. Examples Convert all the GIF files in the current directory to JPEG files, skipping any files which can't be identified or already have existing JPEG files: alchemy -- *.gif -j --W 126 Image Alchemy Wildcard -- Purpose Allow the conversion of multiple files with a single execution of Alchemy. Syntax -- (dash) Comments The wildcard option allows you to specify multiple file names and file names which include wild card characters. Alchemy will perform the same conversion for each input file name that it finds. On MS-DOS systems the use of the wildcard option (--) is not required if the first file name specified includes a wildcard character (* or ?); however to reduce confusion it is still recommended. Limitations The wildcard option (--) must be specified before any file names. If you are using the wildcard option you may not specify an output file name; the file names are automatically generated by substituting an appropriate extension to the input file names. If you do specify an output file name it will be misinterpreted as another input file. An output path name may still be specified. Any error will terminate the execution of Alchemy; any images which appear in the filename list after the one causing the error will not be processed. This includes attempting to overwrite an already existing file without specifying the -o option. Alchemy does not intelligently retain information between files. For example, if you are matching a group of files to an existing palette, the inverse palette generation step only needs to be performed once, but it is in fact done for each file. This only affects the speed of conversions, not the quality. Examples Convert all the GIF files in the current directory to JPEG files: Image Alchemy 127 alchemy -- *.gif -j Convert all the TIFF files in the directory \tiff to PCX files in the directory \images\output: alchemy -- \tiff\*.tif -p \images\output Convert the files madonna.gif, bay4.gif, everest.tga, and basil.tif to JPEG files, overwriting any existing files: alchemy -- -o madonna.gif bay4.gif -j everest.tga basil.tif Convert the files test1.tif, test2.tif, and new*.gif to ILBM files, matching them to the palette from the file output.pal: alchemy -- test1.tif test2.tif new*.gif -f output.pal -i 128 Image Alchemy 6 Colour and Palette Options ------------------------------------------------------------------- Introduction Colour and Palette options are options which affect the appearance of the output image. They control such things as the number of colours in the output image and the dithering techniques used. If you are currently using the Alchemy's menu interface rather than the command-line, you can focus on the purpose, comments, and limitations entries in this chapter. Image Alchemy 129 Black and White -b Purpose Convert the image to black and white. Syntax -b Comments The -b and -c options used in conjunction specifies the number of shades of gray in the image. The default is 256 shades of gray when converting from a true colour image. When converting from a paletted image the number of shades of gray defaults to the number of colours in the original image. The shades of gray are uniformly distributed from 0 to 255. When converting from true colour the image will be changed to a paletted image unless the -24 option is used. Related options -8 Paletted output -24 True colour output -c Specify number of colours Examples Convert the file sample.jpg into a 256 shades of gray raw file: alchemy sample.jpg -b -r Convert the file madonna.jpg into a 4 shades of gray gif file called gray.gif: alchemy -b -c4 -g madonna.gif gray.gif 130 Image Alchemy Colours -c Purpose Specify the number of colours for the output file. Syntax -c colours [reserveColours] Parameters colours Specifies the number of colours in the output image. May be between 2 and 256. reserveColours Specifies the number of colours to reserve in the output image. May be between 0 and 255. Comments If the input file has a larger number of colours than specified for the output file, the image will be quantized using Heckbert's median cut algorithm and dithered. For further information on Heckbert's median cut algorithm see Appendix B, Colour and Dithering. The number of colours to reserve is an optional parameter. If it is present it causes the specified number of colours to be reserved from the beginning of the palette. The output image will not contain any of those colour indices. This can be useful if you have menus or other information you wish to display at the same time as the images and they use colours at the beginning of the palette. The menu colours will then not interfere with the image. The first indices are set to black unless 16 is specified, in which case they are set to the standard VGA colour palette. Limitations Specifying the number of colours only has an effect if you are writing a paletted file (using the -8 option) or if the output file type is always paletted. Converting an image with a large number of colours to a small number of colours (less than 8) will usually give poor results. The reserved colours will be set to black unless 16 colours are reserved. In that case they will be set to the standard VGA colours. Related options -8 Convert to paletted image -d Specify dither type -u Use uniform palette Image Alchemy 131 Examples Convert the image colours.gif into a 16 colour PCX file called colour16.pcx alchemy colours.gif -p -c16 colour16.pcx Convert the image colours.tga into a 256 colour GIF file called output.gif, reserving the first 16 colours. alchemy colours.tga -g -c256 16 output.gif 132 Image Alchemy Dither -d Purpose Specifies the type of dithering to apply to the image. Syntax -d[s] ditherType [perturbation] Parameters If the -d is immediately followed by an 's', then a serpentine raster is used. ditherType can be: 0:None 1:Floyd-Steinberg 2:Stucki 3:Jarvis, Judice, & Ninke 4:Stevenson and Arce 5:Sierra Lite 20:Halftone (clustered dot) 21:Bayer (dispersed dot) 22:Halftone 2 (clustered dot) The default is Floyd-Steinberg. perturbation 0 through 127 The default is 0. Comments Dithering is used to reduce colour banding in an image caused by the palette not having a perfect match for every colour in the image. Types 1 through 5 are all error-diffusion dithers. Types 1 and 5 are the fastest of the diffusion dithers, and they usually look the best on low resolution devices like CRTs. Types 2, 3, and 4 all tend to cause an image to appear more grainy on low resolution output devices (such as CRTs). However, they produce better results than types 1 or 5 on high-resolution, low colour output devices such as laser printers. Type 20 is a digital halftone; this will produce the most accurate grays on a laser printer, but the image won't be as sharp as one produced by the error-diffusion dithers. Type 21 is a dispersed dot ordered dither; it's only advantage over the error-diffusion algorithms is speed. Type 22 is an additional halftone pattern. It's similar to type 20, but with a finer screen. Image Alchemy 133 The -d option only has an effect if the number of colours is being reduced or the image is being re- mapped to a new palette. Specifying a perturbation adds noise to the image, which can help break up visible patterns introduced by dithering. The parameter specifies the magnitude of the noise. Perturbation has no effect on dither types 20, 21, and 22. Using a serpentine raster can also help to reduce visible patterns introduced by dithering. Using a serpentine raster has no effect on dither types 20, 21, and 22. Examples Convert the 256 colour file image.gif to a 16 colour PCX file using a uniform palette and no dithering: alchemy image.gif -p -c16 -d0 -u Convert the true colour image sample.jpg into a 256 colour GIF file called sample.gif, using Stucki dithering: alchemy -g -d2 sample.jpg Convert the 256 colour image sample.gif into a one bit black and white PCL file called sample.pcl, using Jarvis, Judice, and Ninke dithering, a serpentine raster, and a little noise: alchemy -P -b -c2 -ds3 20 sample.gif 134 Image Alchemy EGA Palette -E Purpose Optimize the image quality for display on an EGA board and monitor. Syntax -E Comments If you are converting images to display on an EGA board and monitor this option will optimize the image quality. This option reduces the palette resolution to two bits and automatically specifies the following: -8 -c16 -z0 2 0. Limitations The number of colours in an EGA palette must be less than or equal to 16; the number of colours defaults to 16 but can be reduced by using the -c option. Related options -c specify number of colours Example Convert the image dave1.tga into dave1.pcx, a PCX file with a palette optimized for EGA use: alchemy -E -p dave1.tga Image Alchemy 135 False Colour -F Purpose False colour an image using the palette from a file. The input image will be changed to use the palette found in the specified filename but no attempt at picking the best match will be done. Syntax -F filename Parameter filename Any valid image type which contains a palette Comments This feature can be used to add false colour to monochrome images. The output file is not dithered. This is only applicable to paletted input files. Limitations Cannot be combined with spiff -S or match to palette -f. Example False colour the file scan.gif using the palette from the file colorful.pcx, creating the GIF file new.gif: alchemy -F colorful.pcx -g scan.gif new.gif 136 Image Alchemy Gamma correction -G Purpose Specify the gamma of an input, output, or palette file and/or perform gamma correction. Syntax -G gammaType gammaValue Parameters gammaType: i:Specify input gamma o:Specify output gamma p:Specify gamma of palette gammaValue: 0.0 to 4.0 Comments To perform gamma correction, Alchemy needs to know both the input and output gamma. For some file formats the gamma is known; if you're reading a file with known gamma, such as JPEG, PICT, PCPAINT, or a Targa file with the gamma field, you don't need to specify the input gamma. Likewise, if you're writing a file which has a fixed gamma you don't need to specify an output gamma. Even if reading or writing a file format which has a known gamma you may override it by using the -Gi or -Go option. However, even if both input and output gamma are known based on the input file and the output format, you must still enable gamma correction for any correction to take place; you can do this with just '-G' (if you had specified input, output, or palette gamma, this would be implied). This is because there are quite a few images around that have specified or implied gammas that are wrong, which could cause Alchemy to make matters worse instead of better. Typical values for gamma are 1.0 for images from Macintoshes and 2.2 for images from PCs. Examples To convert the Mac PICT file test.pic, which has a gamma of 1.0, to a PCX file for use on a PC (which should have a gamma of 2.2), use: alchemy -p -Gi1.0 -Go2.2 test.pic Image Alchemy 137 The input gamma could have been omitted, as PICT files have an implied gamma of 1.0, but it's best to include it to reduce confusion. To convert the file image.tga, which has a gamma of 2.2, to a GIF file for use on a Mac, matching the palette test.pal which was created with a gamma of 1.5: alchemy image.tga -g -Gi2.2 -Go1.0 -Gp1.5 - ftest.pal 138 Image Alchemy Match Palette -f Purpose Match the output to a palette read from a file. The input image will be re-mapped to use the palette found in the specified file. Syntax -f filename Parameter filename Any valid image type which contains a palette Comments Using the -f option will cause the output image to be dithered (unless you specify no dithering by using the -d0 option). The -f option can be useful if you are combining several images into a collage or want to match an image to a pre-existing palette. You can also create a custom palette from scratch by using a text editor and creating a .PAL file. Limitations Cannot be combined with spiff -S or false colour - F. The number of colours in the final image will be equal to the number of colours in the palette being read in. The specified file must contain a palette (i.e. cannot be true colour). Related options -l Generate palette file -F False colour -d Dither Examples Convert the image bigimage.tif to a pcx file using the palette from the file standard.pal: alchemy bigimage.tif -p -f standard.pal Convert the image colour.gif to a gif file called colour2.gif using the palette from the file newpal.gif: alchemy -fnewpal.gif -g colour.gif colour2 Image Alchemy 139 Negate -N Purpose Changes the image to a negative. Syntax -N Comments This is equivalent to a photographic negative. When used on black and white images black is changed to white and white is changed to black. On colour images each of the Red, Green, and Blue channels are inverted separately (so that bright blue will become bright yellow). Examples Negate the file sample.gif, generating a GIF file called negative.gif: alchemy sample.gif -N -g negative 140 Image Alchemy Palette -8 Purpose Force the output image to be paletted. Syntax -8 Comments This option is -8 because paletted images are typically 8 bits per pixel. Alchemy defaults to the -8 option if the input file is paletted or gray-scale. Some file formats require files to be paletted; for those formats the -8 option is assumed. Some file formats do not have a paletted variation; in those cases the -8 option will be ignored if specified. Some file formats only allow gray- scale files to be 8 bit; in those cases Alchemy will ignore the -8 option if the image being written is not gray-scale. The actual number of bits per pixel is determined by the -c option (below). If the input file is true colour the output file will be quantized and dithered (see the -c and -d options below). Related options -15 True colour output -16 True colour output -24 True colour output -32 True colour output -c specify number of colours in image -d dither Examples Convert the JPEG file bigimage.jpg into a paletted TIFF file with 256 colours: alchemy -8 -t bigimage.jpg Convert the Targa file madonna.tga to a 16 colour PCX file (note that the -8 option is implied by the use of the -c16 option): alchemy -c16 -p madonna.tga Image Alchemy 141 Palette Selection -z Purpose Control how the palette is generated. These options only have an effect if the palette is being generated by Alchemy using Heckbert's median cut algorithm. Syntax -z sortType [selectionType [swapType] ] Parameters Sort the image palette. SortType can be: 0:None 1:popularity 2:luminance (white to black) 3:rgb 4:luminance (black to white) The default is None. SelectionType can be: 0:mean 1:median 2:corner The default is mean. See Appendix B, Colour and Dithering, for an explanation of these choices. SwapType can be: 0:None 1:IBM (colour 0 is black, 7 is white) 2:Macintosh (colour 0 is white, 255 is black) 3:Sun (colour 0 is white, 1 is black) The default is based on the file type being written out (IBM for GIF, Macintosh for Mac PICT, Sun for Sun Raster, and None for all others). 142 Image Alchemy Comments The most common use for this option is to sort the palette; in this case only a single parameter is needed. This option only affects palettes that are generated by Alchemy. To sort an existing palette you can save the image as a true colour file (such as HSI Raw, by using the -24 -r options) and then convert that back to a paletted file, specifying the desired sort type. In most cases this will not change the image (other than the palette order); however if the palette had entries representing colours that are nearly identical then the image may be modified. Limitations Note that it is not possible to specify a swapType without first specifying both a sortType and a selectionType. See Appendix B, Colour and Dithering, for more information. Example Convert the file input.tga to a gif filed called output.gif sorting the colours by luminance, using the mean of the Heckbert box for the colour, and moving the colours around so that the lightest colour is colour 0 and the darkest colour is colour 1. alchemy input.tga -g output.gif -z4 0 3 Image Alchemy 143 Spiff -S Purpose Enhance the image contrast by stretching the pixel colour values to the full 0 to 255 range. Syntax -S spiffType Parameter spiffType: a:histogram stretching b:histogram linearization c:histogram stretching with b/w ignored The default is histogram stretching. Comments This command can be used if the image you are converting is shifted in brightness or squished in contrast. This can happen if you scan or digitize a very dark or very bright image. The default type, histogram stretching, simply insures that the image has pixels which are distributed over the entire output range (0 to 255). Histogram linearization insures that the distribution of pixels over the output range is linear. Type C spiffing is identical to histogram stretching except that the colours absolute black and absolute white are ignored in the image. This is useful when you have images which have black borders or white captions, since type A spiffing would treat these as part of the image data and not perform any spiffing. Histogram linearization can produce significantly better results than histogram stretching for some images. Generally you will want to try both types to see which gives better results. Limitations The -S option cannot be used at the same time as the -b option when converting from a true colour image. A work around is to do the operation in two steps, converting it to black and white first and then spiffing the resulting image. 144 Image Alchemy Using the spiff option at the same time as the match palette, -f, or false colour, -F, options is not allowed. This is because the spiff option would be performed before the palette is changed, which would nullify the effects. A work around is to do the matching or false colouring first, and then spiff the resultant image. Related options -b Black and White -f Match palette -F False colour image Example Convert the file gloomy.pcx into a PCX file called better.pcx: alchemy gloomy.pcx -S -p better.pcx Do the same thing using histogram linearization instead of histogram stretching: alchemy gloomy.pcx -Sb -p better.pcx Image Alchemy 145 True Colour (15 bits) -15 Purpose Force the output image to be true colour, 15 bits (5 bits per component). Syntax -15 Comments See the True Colour (24 bits) section, below. Related options -8 Paletted output -16 True colour output -24 True colour output -32 True colour output Example Convert the GIF file test.gif into an uncompressed, true colour 15 bit Targa file called test.tga: alchemy test.gif -a0 -15 146 Image Alchemy True Colour (16 bits) -16 Purpose Force the output image to be true colour, 16 bits (5 bits each for red and blue, 6 for green). Syntax -16 Comments See the True Colour (24 bits) section, below. Related options -8 Paletted output -15 True colour output -24 True colour output -32 True colour output Example Convert the GIF file test.gif into an uncompressed, true colour 16 bit Targa file called test.tga: alchemy test.gif -a0 -16 Image Alchemy 147 True Colour (24 bits) -24 Purpose Force the output image to be true colour (not paletted). Syntax -24 Comments This option is -24 because true colour images are typically 24 bits per pixel. Some file formats require files to be true colour; for those formats the -24 option is assumed. Some file formats only have a paletted variation; in those cases the -24 option will be ignored if specified. The file formats which may be either true colour or paletted default to true colour if the input file is true colour. Certain file formats may only be paletted if the images are gray-scale, in those cases Alchemy will automatically switch to true colour if the output image is colour. Converting a paletted image to true colour will not improve its quality or change its appearance. The primary use of this option is to force an image to be true colour when converting to a format which allows either paletted or true colour, but where the paletted variation is not well supported (like the Targa image format). Related options -8 Paletted output Example Convert the GIF file test.gif into an uncompressed, true colour Targa file called test.tga: alchemy test.gif -a0 -24 148 Image Alchemy True Colour (32 bits) -32 Purpose Force the output image to be true colour, 32 bits (8 bits per component, 8 bits for alpha). Syntax -32 Comments See the True Colour (24 bits) section, above. Related options -8 Paletted output -15 True colour output -16 True colour output -24 True colour output Example Convert the GIF file test.gif into an uncompressed, true colour 32 bit Targa file called test.tga (the alpha channel will be empty): alchemy test.gif -a0 -32 Image Alchemy 149 Undercolour Removal -C Purpose Control the undercolour removal process, colour correction, and density correction for output formats which use the CMYK colour space. Syntax -C filename Parameter filename The name of the file which contains the undercolour removal information Comments The undercolour removal portion of the file is compatible with the format used by Stork Colorproofing B.V. The format of this file is described in Appendix G, Undercolour Removal Files. Sample undercolour removal files can be found in the samples directory on the Alchemy distribution disk or tape. Example Convert the file image.tga to an HP RTL file called image.rtl using the undercolour removal file sample.ucr: alchemy image.tga --r4 -Csample.ucr 150 Image Alchemy Uniform Palette -u Purpose Use a Uniform Palette. Syntax -u Comments Instead of using the Heckbert median cut algorithm to generate a custom palette for the image, use a palette with entries which are evenly distributed in the RGB colour cube. The advantage of using a uniform palette is that it's faster than generating a custom palette. However, this is at the expense of image quality since the palette isn't generated based on image content. When just viewing a true colour image on a paletted display a uniform palette is used. The -c option can be used in conjunction with -u to specify the size of the uniform palette; in that case Alchemy will generate a palette with not more than the specified number of colours (but not less than 8). Limitations The palette size will not necessarily match the specified size, as the actual size must be the product of three integers. Alchemy picks integers that roughly correspond to the sensitivity of the human eye to red, green, and blue (30%, 59%, and 11%). Related options -c Specify number of colours -d Dither type Examples Convert the file many.tga to a gif file using a 256 colour uniform palette: alchemy many.tga -g -u Convert the file many.tga to a gif file with up to 128 colours in a uniform palette: alchemy many.tga -g -u -c128 Image Alchemy 151 7 Scaling Options ------------------------------------------------------------------- Introduction These options are all related to image scaling. Note that the -D option does not actually change the size of the image, it specifies an aspect ratio or image resolution to be placed in the header of the output image. If you are using the GUI, you can concentrate on the comments and limitations sections, and ignore the others. 152 Image Alchemy Flip Image -^ Purpose Flip image vertically (turn image upside-down) Syntax -^ Comments Causes the image to be turned upside-down. Examples Convert the Targa file head.tga to another Targa file called tail.tga: alchemy head.tga tail.tga -a -^ Image Alchemy 153 Preserve Aspect Ratio -+ Purpose Preserve aspect ratio when scaling. Syntax -+ (plus) Comments If specified with either the -X or -Y option Alchemy will choose the other dimension to preserve the aspect ratio of the image. If specified in conjunction with both -X and -Y Alchemy will use the values specified as a bounding box, reducing one dimension if necessary to preserve the image aspect ratio. Limitations Does not pay attention to the pixel aspect ratio values in the input image. Related options -X Scale image in horizontal dimension -Y Scale image in vertical dimension Examples Change the size of the image toobig.gif so that the width is 640 and the height is the correct number to preserve the aspect ratio of the image (the new image will be called notbig.gif): alchemy -X640 -+ toobig.gif -g notbig Do the same thing but guarantee that the image will not be larger than 640 by 480: alchemy -X640 -Y480 -+ toobig.gif -g notbig Do the same thing but use better quality scaling: alchemy -Xb640 -Yb480 -+ toobig.gif -g notbig 154 Image Alchemy Scale Image in Horizontal Direction -X Purpose Scale the horizontal dimension of the image to the specified number of pixels. Syntax -X[scaleType] pixels Parameters scaleType The type of scaling to use: a: nearest neighbor b: averaging/linear interpolation c: lanczos2 d: lanczos3 scaleType is optional; the default is nearest neighbor. The higher the scale type the higher the quality (and the longer the processing time). pixels The number of pixels in the output image in the horizontal dimension. Comments Nearest neighbor type scaling is faster than the other types but introduces aliasing (which reduces image quality). The highest quality scaling supported is lanczos3, but it takes much longer than averaging/linear interpolation and generally doesn't produce significantly better results. Limitations All of the scale types other than nearest neighbor give much better results than nearest neighbor scaling, but they are slower and require a new palette to be generated for paletted output files (you can force alchemy to use the original palette by using the -f option and specifying the original image as the palette file). Related options -Y Scale in vertical dimension -+ Preserve aspect ratio Examples Scale the input image, test.gif, to 640 by 480 using good quality scaling, calling the output file test2.gif: alchemy test.gif -Xb640 -Yb480 -g test2.gif Scale the input image, big.tga, using fast scaling to an image which is 320 pixels across and the same aspect ratio as the input image, calling the output file out.tga: alchemy big.tga -X320 -+ -a out Image Alchemy 155 Scale the input image, oddsize.gif, using the highest quality scaling, to an image which is no larger than 640x480, but has the same aspect ratio as the original image, calling the output image new.gif: alchemy oddsize.gif -Yd480 -Xd640 -+ new.gif -g Do the same thing as the previous example, but retain the same palette: alchemy oddsize.gif -Yd480 -Xd640 -+ new.gif -g -f oddsize.gif 156 Image Alchemy Scale Image in Vertical Direction -Y Purpose Scale the vertical dimension of the image to the specified number of pixels. Syntax -Y[scaleType] pixels Parameters ScaleType The type of scaling to use: a: nearest neighbor b: averaging/linear interpolation c: lanczos2 d: lanczos3 The default is nearest neighbor. pixels The number of pixels in the vertical dimension. Comments Nearest neighbor type scaling is faster than the other types but introduces aliasing. The highest quality scaling supported is lanczos3, but it takes much longer than averaging/linear interpolation and generally doesn't produce significantly better results. Limitations All of the scale types other than nearest neighbor give much better results than nearest neighbor scaling, but they are slower and require a new palette to be generated for paletted output files (you can force alchemy to use the original palette by using the -f option and specifying the original file name). Related options -X Scale in vertical dimension -+ Preserve aspect ratio Examples See the -X option, Scale Image in Horizontal Direction, for examples. Image Alchemy 157 Specify Image Aspect Ratio -D Purpose Specify aspect ratio for the output image. Syntax -D aspectRatio Parameter aspectRatio The percentage of the width of a pixel to its height. Comments This option does not actually change the aspect ratio of the image, it just adds the aspect ratio value to the output file. This is important when trying to export the image to software which expects this information. The aspect ratio of an image is the ratio of the width of a single pixel to the height of a single pixel. (So to specify an aspect ratio of 5:6 use -D 83, since (5/6)*100 is 83). Alchemy attempts to preserve the aspect ratio value when converting images whenever one is found in the input image, but since so few file formats have aspect ratio information this hardly ever happens. To write an output image without aspect ratio information specify an aspect ratio of 0 (zero). This option can also be used when displaying an image on an IBM PC. Limitations It is not possible to specify both an aspect ratio and a dots per inch value for an image. This is because specifying a dots per inch value automatically implies an aspect ratio. Many file types do not have an aspect ratio value, so specifying one will have no effect. Related options -D Specify resolution Examples You are converting a 640x350 IBM EGA PCX image called ega.pcx (which has an aspect ratio of 35:48) to a TIFF image and you want the TIFF image to have the correct aspect ratio value (so that an intelligent TIFF reader will correctly interpret the image) (Note that the value of 73 is (35/48)*100): 158 Image Alchemy alchemy ega.pcx -D 73 -t The resulting image will still be 640x350, but the TIFF file now contains the information that the pixels are not square (and in fact are 35:48). If you had instead wanted to convert the image to a 640 by 480 image (with square pixels) you could have used: alchemy ega.pcx -Y480 -D100 -t The -D option isn't really needed here, since any software reading the TIFF file will assume that if there is no aspect ratio specified the pixels are square. Image Alchemy 159 Specify Image Resolution -D Purpose Specify image resolution in dots per inch for the output image. Syntax -D dotsPerInchX dotsPerInchY Parameters dotsPerInchX The resolution of the image in the X direction in dots per inch. dotsPerInchY The resolution of the image in the Y direction in dots per inch. Comments You must specify both dotsPerInchX and dotsPerInchY, even if they are the same. This command does not actually change the resolution of the image, it just adds the resolution fields to the output image. This is important when trying to import the image into software which expects this information. For example, Microsoft Word is much more likely to give the expected results when importing a TIFF image for printing on a laser printer if the image has a resolution of 300 dpi. Reasonable values to use for dotsPerInch include 72 (the resolution of a 13 inch monitor displaying 640x480) and 300 (the resolution of a laser printer). To write an output image without resolution information specify a resolution of 0 0 (zero zero). Alchemy will preserve this information when converting files whenever possible. Limitations It is not possible to specify both an aspect ratio and a dots per inch value for an image. This is because specifying a dots per inch value automatically implies an aspect ratio. This option is ignored when writing a file format which does not have image resolution. Related options -D Specify aspect ratio 160 Image Alchemy Example Convert the Targa file input.tga to a TIFF file called output.tif, specifying that the resolution of the image in the TIFF file is 300 dpi by 300 dpi: alchemy -t input.tga -D 300 300 output Convert the file scan.tif to a DCX variation of a PCX file, scaling the output image to 1500 by 750 (preserving the images aspect ratio) and setting the resolution to 200dpi by 100dpi (this is useful if you will be faxing the image using a fax card): alchemy scan.tif -p1 -X1500 -Y750 -+ -D 200 100 Image Alchemy 161 8 Viewing Options MS-DOS Only ------------------------------------------------------------------- Display Image Alchemy can display images on properly hardware equipped MS-DOS based computers. Depending on the hardware installed, Alchemy supports 320x200x256, 360x480x256, 640x400x256, 640x480x256, 800x600x256, 1024x768x256, 1280x1024x256, 640x480x32768, and 800x600x32768 display resolutions. Alchemy automatically detects which type of display board you have installed. If there are multiple display boards installed in one computer then Alchemy will display images on the first board it finds, searching in the following order: Western Digital based 8514/A board AI compatible 8514/A board VESA compatible SVGA board Other SVGA board. Western Digital 8514/A boards which are equipped with the Western 8514/A Digital chipset are automatically recognized by Alchemy. Depending on the model board and the amount of memory installed, 640x480x256, 1024x768x256, and 1280x1024x256 modes are available. 162 Image Alchemy AI 8514/A Alchemy requires AI to be installed to use 8514/A displays which aren't based on the Western Digital chipset. In addition to 8514/A boards Alchemy should also be able to display on other AI compatible boards, such as 340x0 based boards; however this has not been tested. For AI based boards the only resolution available is 1024x768x256 VESA The best support for SVGA boards is available for VESA compatible SVGA boards. VESA is a SVGA standard which allows applications software, such as Image Alchemy, to interrogate the SVGA board to determine which display modes are available. Some SVGA boards have VESA support built directly into the BIOS found on the board; in this case Alchemy will automatically detect the VESA driver and use it. Other SVGA boards require a software driver to be installed; these drivers are usually found on the floppy disks which came with your SVGA board (typically the driver is called VESA.EXE). If you can't find a driver on the diskettes and the documentation does not explicitly mention that VESA support is built into the BIOS you might call the manufacturer to see if a VESA driver is available. VESA drivers are currently available for VGA boards using chipsets from Cirrus Logic, ATI Technologies, Chips and Technologies, Everex Systems, Genoa Systems, Paradise Logic, Sigma Designs, STB Systems, Tecmar, Headland Technology (Video 7), Orchid Technology, Appian Technology, Trident Microsystems, and Oak Technology. Other SVGA If Alchemy cannot find a VESA SVGA board it attempts to determine what kind of SVGA board is present. The 320x200x256 mode is a standard IBM VGA mode and will work on all VGA boards. The 360x480x256 is a non-standard VGA mode which should also work on all VGA boards. Because of various incompatibilities between different VGA boards, 640x400x256 and/or 640x480x256 modes are not supported on some VGA boards. VGA boards which have been tested for the higher resolution modes include Paradise, Tseng Labs 3000 & 4000, Video 7, Trident, and Everex chipset based VGA Boards. Image Alchemy 163 General Unless you explicitly specify a resolution, Alchemy automatically uses the lowest resolution mode which will display the entire picture. The image will be positioned so that its center coincides with that of the display. 164 Image Alchemy Offset View -_ Purpose The offset view option is used to position the image on the screen during viewing. Syntax -_ xOffset yOffset (dash underscore) Parameter xOffset Number of pixels to shift the image horizontally. yOffset Number of pixels to shift the image vertically. Example View moving the image up 100 pixels: alchemy madonna.gif -v -_ 0 -100 View moving the image to the right 200 pixels and down 50 pixels: alchemy madonna.gif -v -_ 200 50 Image Alchemy 165 View Image -v Purpose View file. Syntax -v horizontalResolution Parameter horizontalResolution 320:Use 320x200 mode 360:Use 360x480 mode 640:Use 640x480 mode 800:Use 800x600 mode 1024:Use 1024x768 mode 1280:Use 1280x1024 mode Comments If displaying on a Western Digital chipset 8514/A or VESA compatible VGA, an optional parameter may follow the -v command. This parameter specifies horizontal resolution and may be 320, 360, 640, 800, 1024, or 1280. The default is to use the lowest resolution which can fit the entire image. If the image is true colour, a uniform palette will be used and the image will be dithered (dithering may be disabled by use of the -d option, see above). See Appendix B, Colour and Dithering, for more information. Related options -V Reduce image to fit display Example View the image madonna.gif: alchemy madonna.gif -v 166 Image Alchemy View Image in True Colour Mode --v Purpose View file using 15, 16, or 24 bits/pixel mode. This allows true colour images to be viewed without dithering to a uniform palette. Syntax --v horizontalResolution Parameter horizontalResolution 640:Use 640x480 mode 800:Use 800x600 mode 1024:Use 1024x768 mode 1280:Use 1280x1024 mode Comments Resolutions above 640x480 are only supported by SVGA boards with a VESA driver. 640x480 mode is supported for various SVGA boards with sufficient memory and the correct DAC. Alchemy automatically picks the highest colour resolution which will fit the image you are trying to view. For example, if your SVGA boards supports 800x600x15 bit and 640x480x24 bit, Alchemy will use the 640x480x24 bit mode when viewing images which are 640x480 and smaller and the 800x600 mode when viewing larger images. You can of course override this by giving Alchemy a resolution parameter after the view command (for example, --v 640, to view in 640x480x24 bit mode). Example View madonna.tga: alchemy madonna.tga --v Image Alchemy 167 View Scaled Image -V Purpose View image while scaling image to fit on monitor and correcting aspect ratio. Syntax -V horizontalResolution Parameter horizontalResolution 320:Use 320x200 mode 360:Use 360x480 mode 640:Use 640x480 mode 800:Use 800x600 mode 1024:Use 1024x768 mode 1280:Use 1280x1024 mode Comments This command will scale the image and correct the aspect ratio of the image by removing rows and/or columns from the image. Note that this option can also be useful for displaying images which are not larger than the screen but which have an aspect ratio different than the display. Limitations Alchemy assumes that the aspect ratio of a display pixel is 1:1 when in 640x480, 800x600, 1024x768, and 1280x1024 modes, 5:6 when in 640x400 mode and 320x200 modes, and 16:9 in 360x480 mode. If not otherwise specified by using the -D option or in the file, Alchemy assumes that the aspect ratio of pixels in 640x400 images and 320x200 images is 5:6 and the aspect ratio of pixels in 640x350 images is 35:48. You can override any of these assumptions with the -D option. Don't worry if this is confusing; in practice Alchemy deals with everything automatically if you use the -V option. However, there is a problem with displaying 320x400 IFF files; see Appendix A, Answers to Frequently Asked Questions, for more information. Related options -D Specify image resolution -v View image Example View madonna.gif: alchemy madonna.gif -V 168 Image Alchemy View Scaled Image in True Colour Mode --V Purpose View image in 15 bit mode while scaling image to fit on monitor and correcting aspect ratio. Syntax --V horizontalResolution Parameter horizontalResolution 640:Use 640x480 mode 800:Use 800x600 mode 1024:Use 1024x768 mode 1280:Use 1280x1024 mode Comments Requires either a Tseng 4000 equipped SVGA, an S3 equipped SVGA board, or a VESA compatible SVGA board with a Sierra DAC and 1 Megabyte of memory on the SVGA board. This command will scale the image and correct the aspect ratio of the image by removing rows and/or columns from the image. Note that this option can also be useful for displaying images which are not larger than the screen but which have an aspect ratio different than the display. Limitations The same limitations as for scaled 8 bit viewing apply (see page 7-7 in the User's Manual). Related options -D Specify image resolution --v View image in 15 bit mode Example View sample.jpg: alchemy sample.jpg --V Image Alchemy 169 9 Tutorial and Examples ------------------------------------------------------------------- Introduction This section gives a sample session of using the command-line version of Alchemy. It is assumed that you have installed Alchemy as instructed by the installation section of the manual. The sample image file, sample.jpg, which can be found in the samples directory on the distribution disk or tape, must be in the current directory. Examples We will use the sample.jpg image supplied in the \samples directory. The first step is to copy this into the directory with Alchemy. copy samples\sample.jpg Now we will convert this JPEG file to a GIF file. Notice that we don't have to specify an output file name. Alchemy will automatically supply the name sample.gif. alchemy sample.jpg -g We can then view this GIF file using Image Alchemy (assuming you have a compatible Super VGA card): alchemy sample.gif -v To convert the sample.gif file to a PCX file called test1.pcx do the following: alchemy sample.gif test1.pcx -p You can now view this file by doing: alchemy test1 -v Note here that Alchemy automatically added the extension .pcx since none was supplied. Let us now convert the test1.pcx file to a small TIFF file called test1.tif, we will scale the TIFF file to be 200x100 pixels. To perform the scaling we will use -X and -Y options: alchemy test1.pcx -t -Xb200 -Yb100 170 Image Alchemy In this case we specified that Alchemy should use type B scaling. This is a good scaling type to use for general purpose scaling (type A scaling is faster but not as good a quality, whereas Type C and Type D scaling are better quality but slower). You can now view this TIFF file by using: alchemy test1.tif -v If you had wanted to view it using the standard VGA mode 320x200 you could have used: alchemy test1.tif -v320 To convert this TIFF file to a gray-scale PCX file use alchemy test1.tif -b -p -o The -b option indicates black and white and the -o option tells Alchemy that it is okay to overwrite the existing test1.pcx file. You can now view this PCX file by using: alchemy test1.pcx -v To convert the JPEG file sample.jpg to a Targa file called sample.tga use the following command: alchemy -a sample.jpg To convert the 24 bit Targa file sample.tga to a 256 colour GIF file called new.gif: alchemy -g sample.tga new.gif To convert the 256 colour GIF file, new.gif, to a 64 colour PCX file called new.pcx: alchemy -p -c64 new.gif To view the GIF file new.gif (only applicable on IBM PCs with appropriate VGA board): alchemy -v new.gif Image Alchemy 171 To convert sample.jpg to a black and white, two colour GIF file use a text editor to create a file called BW.PAL which contains the following: PAL 2 0 0 0 255 255 255 then: alchemy -g sample.jpg -f bw.pal (Alternatively, you could have said alchemy -g sample.jpg -b -c2, but that wouldn't have demonstrated the -f option). To view the resulting file in 320x200x256 mode, scaling the image to fit the display: alchemy -V320 sample.gif To create a LZW compressed TIFF file called new.tif which is 320x240 from the targa file created earlier, using good quality scaling: alchemy sample.tga -t1 -Xb320 -+ new.tif 172 Image Alchemy A Answers to Frequently Asked Questions ------------------------------------------------------------------- Question When I view a JPEG compressed image on my VGA board it looks much worse than when I first convert it to a GIF file and then view it. Why is this? Answer To save time Alchemy automatically uses a uniform palette when you are just viewing a true colour image. When converting to a different file format Alchemy uses Heckbert quantization to generate a palette. The difference in image quality is the difference between using a uniform palette and an optimum palette. See Appendix B, Colour and Dithering, for more information on palette generation. Question Why can't my paint package read the Targa file I wrote with Image Alchemy? Answer Some software which reads Targa files cannot handle compressed files. In addition, some software can read true colour Targa files, but cannot read paletted or gray-scale files. Image Alchemy can be forced to write out a true colour file by using the -24 option. Question I told Alchemy to convert a PCX file to an 8 bit GIF file (using the -8 option). Yet when I get statistics on the file (using -x) Alchemy reports the file only has 16 colours. Answer Alchemy will always store the file using the smallest bits-per-pixel allowable for the given image (this results in the smallest possible file). In this case the input file only had 16 colours in it. Image Alchemy 173 Things get more unpredictable with formats such as Sun Raster (which requires 1 bit files to be black and white) and SGI (which requires 8 bit files to be gray-scale). In these cases Alchemy will always do the best it can (giving you a warning message if it does something which may surprise you later). Question Why is decompressing or compressing a JPEG image so slow? Answer There are a large number of calculations that have to be done during JPEG compression. This is an inherent limitation of JPEG compression. Image Alchemy has been optimized quite a bit to reduce the number of calculations, and we are working to further reduce the number of calculations. If you are transferring files over modems or storing them on slow media (tape) the compression times are usually more than made up for by the decrease in transmission or retrieval times. Question Why can't my favorite desktop publishing package read the TIFF file I wrote with Image Alchemy? Answer Tagged Interchange File FormatTIFF is an extremely versatile standard; it can handle anything from 1 bit images to full colour images with an alpha channel. Also, TIFF allows many different types of compression. Unfortunately this versatility means that it's difficult for a single piece of software to be able to read in every valid TIFF file. If the software specifies the classes of TIFF it can read, you can force Alchemy to write out a specific TIFF class by using the following options: class B: -8 -b -c2 -t2 class G: -8 -b -t1 class P: -8 -t1 class R: -24 -t1 Class B is black and white, Class G is gray-scale, Class P is paletted, and Class R is true colour. 174 Image Alchemy If the supported classes are not specified, experiment with various combinations of -24, -8, - b, and -c. In this case it is usually best to use no compression (-t0) while experimenting with the other options, as many TIFF readers have difficulty with compressed files. When you find a set of options that work, then you can try various compression modes to save space. Be aware that using the -b option will force the output file to be gray-scale and you will lose the colour information in the file (most desktop publishing programs only have support for gray-scale TIFF files). You may also have to use the -Dn n option to specify the resolution of the image (this is especially true when converting from a file format which does not have a value for image resolution). You can generally tell if this is necessary because the program you are using to read in the TIFF file will claim that the file is unreasonably large or small. Generally, if you are using a 300 DPI Laser Printer you want to make the TIFF file 300DPI x 300DPI (-D 300 300). If you would like further information specific to using Image Alchemy with your word processor or desktop publishing program please contact us; we will be maintaining a list of how to make Alchemy work with other software packages. Similarly if you figure out how to import files into a specific package let us know and we will add your tips to our documentation. Image Alchemy 175 Question I've converted a Mac PICT file to a GIF file, but the GIF file is missing some or all of the information that was in the PICT file. What happened to it? Answer PICT files are a combination of drawing commands (such as lines, rectangles, and circles) and raster areas (called pixMaps). Alchemy can only read the raster portions of the files. Programs such as MacDraw and MacDraft write out files with drawing commands, programs such as MacPaint write out files which are entirely raster areas (pixMaps), and some programs, such as SuperPaint can write out files which are either, or a combination of both. If you are using such a program check the documentation on how to write out files in "paint" mode. Question When I convert a GIF file to a JPEG file and then back to a GIF file the final GIF file is twice the size of the original. Why is this? Answer There are two things which might cause this to happen: JPEG compression doesn't really work well for images which have large areas which are all the same colour. The reason for this is that JPEG is a lossy compression technique. Therefore you are not going to get back exactly the same values for each pixel in an area that was one solid colour before being JPEG compressed. But GIF compression works much better on areas which are one solid colour, so, when you GIF compress these areas, they are quite a bit larger than they were before. The solution to this problem is to use HSI JPEG compression, which automatically detects large areas of solid colours and does not JPEG compress them. The problem with HSI JPEG compression is that it isn't compatible with JPEG or JFIF. 176 Image Alchemy The other possibility is that the input GIF file didn't have very many different colours. When you converted it to a JPEG file the number of colours in the file was lost (JPEG gray-scale files always use 256 shades, and JPEG colour files are always true colour). When the JPEG file was converted back to a GIF file Alchemy assumed you wanted 256 colours in the file, and a 256 colour GIF file is bigger than a 16 colour GIF file. To prevent this you can use a -c32 (or however many colours the original had) option in the command line; this forces Image Alchemy to use that many colours for the output file. Question I keep getting "Out of Memory trying to ..." messages. Help! Answer Image Alchemy is running out of memory. First try to do the conversion again with the -$ (conserve memory) option. Next, if that doesn't help, attempt to maximize the amount of memory available by removing as many memory resident programs as you can. If this still doesn't help please contact us with the following information: your computer configuration (amount of available memory, size of hard disk), operating system version, and what you are trying to do (input file information (size of image and type of file) and options specified). Alchemy can generally convert images as larger than 2000 pixels wide and a virtually unlimited number of pixels tall. However there are certain conversions which require more memory than others. Question I am using Alchemy to display a 320x400 IFF image created by an Amiga. When I use just the -v option the image comes out tall and skinny. When I use the -V option, which is supposed to correct the aspect ratio, things get worse instead of better (the image is even skinnier). What's going on? Answer As near as we can tell, some Amiga software has a different idea of what aspect ratio is than the rest of the world. Image Alchemy 177 For displays, aspect ratio is defined as the ratio of the width of a single pixel to the height of a single pixel. So if you have square pixels (which you do on a standard monitor in 640x480 mode) the aspect ratio is 1 to 1 (commonly written as 1:1). When you change display modes the height and width of the total display area does not change; what is changing is the width and height of each pixel, which means that the aspect ratio changes. For example, a 640x400 display has an aspect ratio of 1:1.2 (that means each pixel is 1.2 times as tall as it is wide (which makes sense since 480/400 equals 1.2)). A 640x200 display has an aspect ratio of 1:2.4. Now this is where it gets interesting in terms of IFF files. The aspect ratio number stored in Amiga IFF files for 320x400 images is 1:1.1, meaning pixels are 1.1 times as tall as they are wide, so therefore the actual image should be the equivalent size of a 320x440 image with square pixels. And this is what Alchemy will attempt to display when you use the -V option (Alchemy never makes any dimension larger, so the actual image Alchemy displays is 291x400, which is the same ratio as 320x440). However this is obviously wrong, as you can tell when you examine an image. As near as we can tell the correct aspect ratio of these images is 5:3 (the math we used to come up with this number is 640/320:480/400). And if you tell Alchemy to override the aspect ratio by using a -D 167 option (167 because 5/3*100 is 166.6666) the image displays correctly. Why Amigas create images which claim they are 1:1.1 remains a mystery. 178 Image Alchemy Question When I convert a 32 bit Targa file to a GIF file and then to a JPEG file it doesn't look nearly as good as if I convert the Targa File directly to the JPEG file. What can I do to maintain high quality in JPEG compressed files? Answer When the Targa file was converted to the GIF file Image Alchemy had to reduce the number of colours in the file (the original Targa File had up to 16 million colours, GIF files are limited to 256 colours). This step is known as colour quantization (Image Alchemy uses the Heckbert Median Cut method for quantization, see Appendix B, Colour and Dithering, for more information). The difficulty with colour quantization is that it leaves artifacts known as colour banding. To reduce this phenomenon Image Alchemy dithers the image (you can see the effect of colour banding by turning off dithering by using the -d0 option). Unfortunately a dithered image does not JPEG compress very well (dithering adds a lot of high- frequency information to an image; JPEG compression attempts to remove much of that information). In addition JPEG images are always continuous colour images, so when the JPEG file is decompressed it has to be colour quantized and dithered again. Dithering a previously dithered image reduces the quality even more. The solution is to use the best starting quality you can for JPEG compression, ideally a continuous tone image. The compressed image size will be smaller than if you had started with a paletted image and the quality will be better. Question I've converted an HP PCL file to a GIF file, but the GIF file is missing some or all of the information that was in the PCL file. What happened to it? Answer PCL files have the same problem as PICT files (see above); they are a combination of drawing commands (such as lines and rectangles) and raster areas (called rasters) and Alchemy can only convert the raster areas in PCL files. PCL Files also contain font and text information, which is also lost. Unfortunately there isn't any general way to preserve this data with Alchemy. Image Alchemy 179 One thing which you can do if running Microsoft Windows 3.0 is to install Adobe Type Manager (ATM). ATM automatically intercepts any text commands and converts them to rasters. In addition, the standard Windows 3.0 HP PCL driver only generates rasters, not vectors. So the file will appear in its entirety when converted by Alchemy. Contact us if you want further information on using Alchemy with Windows 3.0. Question Why can't Image Alchemy read in JPEG files produced by Kodak's ColorSqueeze (or Sun's VFCtool)? Answer The JPEG standard is still in draft form. Until it is a mature standard, various manufacturer's will implement different versions of it. As of March 1, 1991 Image Alchemy supports the JFIF format and should work with any other JPEG software which also claims JFIF compatibility. If other software you are using claims to support the JFIF format and you are having trouble please contact us. If the other software does not support JFIF, contact the manufacturer and tell them they should send you an update which does (you can tell them to contact us if they need a copy of the JFIF standard). Question I converted a PCX file with 16 colours to a 16 shades of gray TIFF file using the -b and -t options. The 16 colour PCX file had some shades of gray in it which were changed in the TIFF file. How can I prevent this? Answer The problem is that gray-scale TIFF files have a uniformly spaced gray palette. If you create a TIFF file with 16 shades of gray it will have the following shades in it: 0, 17, 34, 51, 68, 85, 102, 119, 136, 153, 170, 187, 204, 221, 238, and 255. However the 16 colour PCX file you started with probably didn't have those exact colours in it (for example, PCX files written out by Windows 3.0 Paint have shades of gray which correspond to 0, 128, 192, and 255). So Alchemy did the best it could and matched the input colours to the output colours (and depending on the other options that you specified may also have dithered the image). 180 Image Alchemy The solution is to tell Alchemy to write out a 256 colour gray-scale TIFF file (which you do by adding a -c256 to the -b and -t options). This file still has a uniform gray palette; but that palette now contains every colour: 0, 1, 2, 3, ..., 255. Therefore Alchemy can map, for example, the colours 128 and 192 to their exact match. This does have the disadvantage of making the resulting 256 colour TIFF file twice as large as the 16 colour TIFF file, but this is the only way to guarantee that Alchemy can find an exact match for all the shades of gray in the input file. Question Why do you only allow specifying image resolution in Dots Per Inch? Don't you realize that most of the world is metric? Answer Yes, we do realize that the entire world, with the exception of the United States and Great Britain, claims to use the metric system exclusively (and Great Britain will presumably change in 1992). However, this isn't actually true. A laser printer manufactured in Japan is still 300 dots per inch (not 11.811... dots per mm) and a 19 inch monitor sold in Europe is called a 19 inch monitor (actually a 19 inch monitor is called a 20 inch monitor in Europe, which is a measure of the total picture tube diagonal, not just the viewing area). Question How do I get a copy of the current draft JPEG standard? Answer The JPEG standard is a ISO/IEC standard currently in Committee Draft form. Contact your local ISO/IEC office to get a copy. The reference numbers are ISO/IEC JTC 1 and /SC 2 N2215; the document number is ISO/IEC CD 10918-1. In the United States you can contact ANSI at: ANSI 11 West 42nd St. New York, NY 10036 (212) 642-4900 Question Do you give multiple copy discounts? Do you have site licenses? Are you interested in licensing the source code? Answer Yes. Yes. Yes. Contact us for more information. Image Alchemy 181 182 Image Alchemy B Colour and Dithering ------------------------------------------------------------------- Paletted vs. Colour images are normally stored in one of two true colour ways: as an array of direct colour values (usually red, green, and blue) (referred to as a true colour file in this document) or as an array of indices into a colour-map which contains red, green, and blue colour values (referred to as a paletted file in this document). The reason for the existence of paletted images is that they take less memory, so the hardware to display them is less expensive. The dominance of paletted hardware is changing as the price of memory and the processing power it takes to update large amounts of memory at a reasonable speed drops (a Targa 32 board is an example of a true colour board, a VGA board is an example of a paletted board). Until true colour graphics devices become the norm, there is a need to convert images from true colour to paletted. This conversion is done in two steps: the first is to generate a palette for use by the image; the second is to map the image to the new palette. Colour cube The colour model generally used by computers is a cube with red, green, and blue as the axes (this is known as a colour cube or RGB cube). Each point inside the cube is a different colour, depending on the amount of red, green, and blue used. In nature each of the three axes is nearly continuous, therefore there are a nearly infinite number of colours available. Computer hardware and software represent colours in a discrete fashion. Image Alchemy 183 For true colour displays or file formats the number of discrete positions along each axis of the colour cube gives the colour resolution of the output device. For example, a Targa 24 board for an IBM PC has 8 bits per red, green, and blue channel for a total of 24 bits (or 256 discrete shades of each colour, for a total of 16 million colours (256x256x256)). This is also the colour resolution of most true colour file formats. The new 15 bit SVGA boards have 5 bits per channel, for a total of 32x32x32 different colours (32,768). This is the same colour resolution as a Targa 15 file. A paletted display or image file has the same colour resolution limit as a true colour display or image file, but in addition there is a limit on how many points inside the cube can be used at the same time. An 8 bit file format, such as GIF, allows 256 different colours out of 16 million. A normal SVGA board also only allows 256 different colours at one time. So, converting a true colour file to a paletted file involves reducing the number of occupied points in the colour cube. There are several ways this can be done. Generating a Image Alchemy supports two methods of generating a palette palette: Uniform The simplest and fastest method is to use a palettes palette containing colours which are uniformly distributed in the RGB cube, referred to as a uniform palette. This has the advantage that it's fast and the same palette can be used for any image; the primary disadvantage is that most images don't contain colours from everywhere in the RGB cube, so palette entries are wasted representing colours that aren't needed for the particular image being converted. 184 Image Alchemy Optimal To generate a palette which is better for palettes representing a particular image, Image Alchemy supports Heckbert's median cut algorithm. This algorithm first builds a three dimensional table (a histogram cube) indicating how popular any given colour in the RGB cube is in the image being converted. It then proceeds to subdivide this histogram cube (by dividing boxes in half) until it has created as many boxes as there are palette entries. The decision as to where to divide a box is based on the distribution of colours within the box. This algorithm attempts to create boxes which have approximately equal popularity in the image. Palette entries are then assigned to represent each box. There are other methods of generating a palette from an image, but Heckbert's algorithm is generally regarded as the best tradeoff between speed and quality. Modifying the You can change the method used to select a colour palette to represent each box by use of the -z options. selection process The default method is to use the mean of all the colours in the box. However for some images slightly better results can be obtained by using the center of the box (without regard to where the pixels are in the box). For images being reduced to a very small number of colours (less than 16) better results can be obtained by using a corner of the box (the boxes tend to be large when reducing an image to a small number of colours; therefore picking colours near the centers of the boxes will give you muddy colours, while using corners of the boxes will give you more saturated colours). Mapping the The next step is to map the image to the new image to the palette; this is where dithering becomes palette important. Image Alchemy 185 No dithering The simplest approach is to map every colour in the original image to the palette entry which is closest to it (this is what Image Alchemy does if you specify no dithering). However, since the palette entries generally represent several different colours in the original image, this results in colour banding where areas of smooth colour changes in the original become areas of one solid colour in the paletted version. Advantages of This can be alleviated by dithering the image data dithering such that any given pixel might not be mapped to its closest palette entry, but the average over some area of the image will be closer to the correct colour than it would otherwise be. Image Alchemy uses a class of algorithms called "error- diffusion" to do dithering. Error diffusion These algorithms work by using the closest palette dithering entry to a colour and then distributing the error (the difference between the desired colour and the chosen palette entry) to the nearby pixels. This process is repeated for every pixel in the image, using the colour values which have been modified due to the error from previous pixels. The different dithering algorithms spread the error over a different area or use a different weighting within the same area. Serpentine Error diffusion can be done as a normal raster raster (left to right, top to bottom) or as a serpentine raster (alternating left to right and right to left, top to bottom). A serpentine raster tends to break up visible patterns introduced by dithering. Noise Random noise can also be added to help break up visible patterns in the resulting image. Further For more information on Heckbert's median cut and information dithering see the appropriate reference listed in the References section below. 186 Image Alchemy C What is JPEG Compression? ------------------------------------------------------------------- Who are those JPEG stands for the "Joint Photographic Experts JPEG guys? Group". This is a group of experts who defined a standard compression scheme for still images, commonly called JPEG Compression. Currently the standard is still in draft form. The standard should be finalized in 1991. Overview JPEG Compression consists of a series of reasonably complex mathematical operations. These include: colour space conversion, discrete cosine transforms, quantization, and entropy coding. After these steps you end up with an image which takes fewer bits to store than you started out with. However, when you decompress a JPEG compressed image you end up with an image that is not quite the same as the original (which is why JPEG Compression is referred to as "lossy"). Is lossy You might well ask why anyone would want to compression compress an image using a lossy technique. bad? Compression ratios for lossy compression are much better than for lossless compression and the loss is generally very small. And, in fact, every operation of converting an image is lossy (the original photographic or electronic process which captured the image was lossy, scanning or digitizing the image was lossy, displaying the image on a monitor is lossy, and printing the image is lossy). Details JPEG compression involves the following steps: Image Alchemy 187 Step 1 The image is converted to a colour space with separate luminance and chrominance channels. This is done because the human eye is far more sensitive to the luminance information (Y) than it is to the chrominance information (Cb and Cr); by separating them, it's possible to compress the chrominance information more than the luminance before the perceived image quality suffers. This step isn't specified in the JPEG draft (it doesn't discuss colour space at all), but is standard practice. Image Alchemy uses CCIR-601 YCbCr, which is the colour space specified by the JFIF standard. Step 2 The luminance and chrominance information are separately transformed to the frequency domain using a discrete cosine transform acting on 8x8 pixel blocks. To reduce the amount of data which needs to be compressed the chrominance information may be sub- sampled first. Alchemy uses 2h:1v:1h:1v:1h:1v sub-sampling when writing JPEG files, which means that the first component (luminance) has twice as many samples horizontally as the other two components (chrominance), and the same number of samples vertically. Alchemy can read JPEG files with any sub-sampling allowed by the draft standard. Step 3 quantizationThe transformed data is quantized (so some information is thrown away). The samples representing higher frequencies are generally quantized using larger steps than those representing low frequencies. The quality level you specify is used to scale a set of quantization values which have been found to cause the quantized data to all have approximately equal importance visually. A lower quality number will cause larger quantization steps to be used, and hence increase the compression ratio and decrease the image quality. 188 Image Alchemy Step 4 The quantized data is compressed using an entropy coder. Huffman and Arithmetic coding are allowed by the draft JPEG standard; only Huffman coding is allowed by the JFIF standard. Huffman coding can either be done with a set of fixed tables or custom tables can be generated for an image. Alchemy, by default, uses a fixed set of tables, but can also generate custom tables which usually produce 5-20% (depending on the image and quality setting) better compression. However, producing custom tables requires an additional pass over the image data and therefore takes a little longer. Alchemy can write JPEG files using either Huffman or arithmetic coding; arithmetic coding generally results in a slightly smaller file, but at the cost of non-JFIF compatibility and longer compression and decompression times. JPEG This data corresponds to the JPEG Interchange Interchange Format and is ready to be stored in a file. Format Unfortunately the JPEG Interchange Format does not include enough information to actually be able to convert the file back to an image. Specifically the colour space used and the aspect ratio or resolution of the image are not included. Until recently there was no standard way of putting this information in a JPEG file. JFIF On March 1, 1991 representatives of several JPEG hardware and software developers (including C- Cube, Radius, NeXT, Storm Tech., the PD JPEG group, Sun, and Handmade Software) met at C-Cube and established the JPEG File Interchange Format (JFIF). If you would like more information on the JFIF standard please contact us. Image Alchemy 189 D Customer Support ------------------------------------------------------------------- Why might We have made every effort to insure that Image Alchemy mess Alchemy can read all files in its supported up? formats. However, because of poorly written standards and non-adherence to standards there are undoubtedly certain files that Image Alchemy does not read correctly. What we need to If you come across any files which Image Alchemy help you has trouble with please contact us with as much of the following information as you have: version of Image Alchemy you are using, type of file, type of computer which generated it, name and version of software which wrote the file, size of image, and the number of colours in image. We may ask you to send us the file so that we can figure out what went wrong. If you send us a file we will attempt to modify Image Alchemy so that it can read the file. Once Image Alchemy is modified, we will send you an updated copy of Image Alchemy. Similarly, if any files that Image Alchemy writes cannot be read by other software please contact us. We may ask you to send us a copy of a file that can be read by that software package for comparison. Please contact us even if you are just using a demo copy of Alchemy. In addition to helping fix a potential bug, we feel the best way to get you to purchase a copy of Alchemy is to demonstrate how committed we are to customer support. 190 Image Alchemy How to contact Our address and phone numbers are: us Handmade Software, Inc. 15951 Los Gatos Blvd., Suite 17 Los Gatos, CA 95032 +1 800 358 3588 (Toll-free from the U.S.) +1 408 358 1292 (Voice) +1 408 358 2694 (Fax) The most efficient way to contact us is by e-mail; this is especially true if you can send us a sample file which demonstrates the problem. Our e-mail addresses are: Internet: hsi@netcom.COM CompuServe: 71330, 3136 We also have a 24 hour bulletin board BBS where you can upload and download files. It speaks 2400 baud, 9600 baud (v32, v42, and v42.bis), and PEP and its number is: +1 408 356-3297 (BBS) Image Alchemy 191 E Binary Information Files (BIF) ------------------------------------------------------------------- Overview Binary files are image files which are just data. In other words, they do not contain any information other than the actual pixels in the image. In order to read these files you must create a file using a text editor which describes to Alchemy the format of the file you are trying to read in. This is called a BIF file (and normally has the extension .bif). Required At the minimum a BIF file needs to contain the information filename of the image file and either the height or the width of the image. Alchemy will make assumptions about the other characteristics of the image based on the information that it is given and the total length of the image file. BIF file format The first line contains the letters BIF, which identifies the file as a BIF file. Each of the rest of the lines in the BIF file consist of an information tag followed by the information. The spelling of the tags must be exact or Alchemy will report an unknown tag error. 192 Image Alchemy Tags Tag Description filename The name of the file containing the binary data. width The width of the image data, in pixels. height The height of the image data, in pixels. planes The number of planes of image data (1, 2, 3, or 4). A 1 plane image is assumed to be gray-scale, a 2 plane image is a gray-scale image with an alpha channel, a 3 plane image is a RGB image, and a 4 plane image is a RGB image with an alpha channel. header The size of the header, in bytes. This many bytes will be skipped when reading the file. leftpadding The number of bytes to remove from the beginning of each scan line. rightpadding The number of bytes to remove from the end of each scan line. order The order of the pixels. For 3 channel images, this can be any sequence of r, g, and b: rgb, rbg, grb, gbr, brg, or bgr (r=red, g=green, b=blue). For 4 channel images, this can be any sequence of a, r, g, and b (a=alpha). Either ga or ag for 2 channel images (g=gray, a=alpha). The defaults are g, ga, rgb, and rgba, depending on the number of planes. upsidedown The presence of this tag indicates that the data in the file is recorded from the bottom of the screen up to the top of the screen. Comments Lines beginning with a # are treated as comments. Comments and blank lines are ignored when processing the file. Image Alchemy 193 Palette files If the binary file has a palette available, you can use that palette by writing custom software to convert it to a .PAL file and using the -F option while reading the BIF file. Example This is an example BIF file which can be used to read a 640 pixel wide, true colour HSI Raw file. Note that HSI raw files have a 32 byte header which is being skipped. Of course you could read the Raw file directly using Alchemy, but this is after all an example of a BIF file. BIF width 640 #skip past header header 32 filename sample.raw planes 3 #the tag below isn't actually needed, #since rgb is the default, but is #included here to give an example of #what an order tag looks like order rgb Using the Assuming the BIF file is called sample.bif, the example BIF following Alchemy command can be used to convert file the image to a GIF file: alchemy sample.bif -g The height of the image will be automatically calculated from the length of the file and the width, header, and planes tags. A BIF file is treated as an ordinary file, so all the standard Alchemy commands may be used. 194 Image Alchemy F HSI Raw Files ------------------------------------------------------------------- History The HSI Raw format was originally intended as an internal format to Image Alchemy. Because of user demand the format has been documented to allow others to read and write HSI Raw files. Overview HSI Raw files are completely uncompressed, unpacked, and unpadded image data files. Therefore they tend to be larger than almost any compressed file format. However, they have the advantage, as far as Alchemy is concerned, that they are very fast to read and write and the location of any pixel in the image may be found by simple calculations. If you need to convert custom files to a format that Alchemy can read we recommend using a Raw file; it is the simplest format to write and the fastest for Alchemy to read. Variations There are two types of HSI Raw Files: paletted and true colour. Paletted images are stored one byte per pixel with a palette at the beginning of the file. True colour files are stored three bytes per pixel. Gray-scale Gray scale files are stored as paletted files with a palette that contains all gray values. Alchemy automatically recognizes such files during reading and will treat them appropriately. Black and white Black and White files are stored as paletted files with a palette that contains two values, black and white. Alchemy automatically recognizes such files during reading and will treat them appropriately. Warning Note that Handmade Software, Inc. reserves the right to make changes to this format at any time and without notice. And while it is unlikely, it is possible that future versions of Image Alchemy will not support this format. Image Alchemy 195 Old version This appendix describes version 4 Raw files. This files is the version that Image Alchemy has written since March 1991. Before this Alchemy wrote version 2 and 3 raw files (version 2 were 8 bit files, version 3 were 24 bit files). Those raw files can be read by current versions of Image Alchemy but are not otherwise supported. If you run across any of these raw files the easiest thing to do is to use a current copy of Alchemy to convert them to a version 4 raw file. Details Word size All values which are not otherwise identified are two byte integers (16 bits). This is the native integer size of most IBM PC C-compilers but not for Macintosh and Sun C-compilers. Byte order All integers are stored high byte first (big- endian order). This is the native mode for Macintosh's and Sun's but not the native mode for IBM PC's. See below for a CPU independent method to read and write 2-byte integers. Pixel format Paletted files are stored one byte per pixel. True colour files are stored as three bytes per pixel in red, green, blue order. Padding Neither the palette information nor the pixel data is padded to anything other than a byte boundary. This means that if you store a file which is 13 by 11 pixels it will occupy 429 bytes if stored as a true colour file (not including the header), or 143 bytes if stored as a paletted file (not including the header and palette data). Hex Numbers including a 0x prefix are hex; all other numbers are decimal. File format The header for a paletted file is 32 bytes plus the size of the palette. The header for a true colour file is exactly 32 bytes (a true colour file contains no palette). 196 Image Alchemy Magic number Six bytes used to identify the file as a HSI Raw file: 0x6d 0x68 0x77 0x61 0x6e 0x68 Version An integer used to identify the version HSI file: 0x0004 Width An integer indicating the width of the image (in pixels). Height An integer indicating the height of the image (in pixels). Palette size An integer indicating the number of entries in the palette. Range is 2 to 256. A 0 or -24 indicates a true colour image (which has no palette data). Horizontal DPI An integer indicating the horizontal resolution of the image, in dots per inch. A zero indicates that the resolution is unknown. A negative number is used if only the aspect ratio is known. Vertical DPI An integer indicating the vertical resolution of the image, in dots per inch. A zero indicates that the resolution is unknown. A negative number is used if only the aspect ratio is known. Gamma An integer indicating the gamma of the image, scaled by 100 (a gamma of 2.2 is stored as 220). A zero indicates that the gamma is not known. Reserved Twelve bytes reserved for future use. Should be set to zero when writing. Palette The palette data is stored as 3 bytes per palette entry. The bytes are in red, green, blue order; 0 is black, 0xff is full intensity. True colour raw files have no palette. Image data The image data. Example files Image Alchemy 197 8 bit paletted, 6D 68 77 61 6E 68 00 04 01 40 00 C8 01 00 00 00 320 x 200: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 49 24 24 24 00 00 00 00 00 DB 6D 6D FF 92 92 FF B6 B6 92 49 49 FF DB DB FF B6 92 FF FF DB FF DB B6 FF FF FF B6 6D 6D 6D 24 24 DB 92 6D 6D 49 49 ... 24 bit true 6D 68 77 61 6E 68 00 04 01 40 00 C8 00 00 00 00 colour, 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 320 x 200: 49 24 24 49 24 24 49 24 24 49 24 24 49 24 24 49 24 24 49 24 24 49 24 24 49 24 24 49 24 24 49 24 24 49 24 24 49 24 24 49 24 24 49 24 24 49 24 24 ... Reading a two byte integer int getWord(int i, FILE *stream) { register int temp; temp=getc(stream)<<8; return(getc(stream) | temp); } Writing a two byte integer int putWord(int i, FILE *stream) { putc(i>>8, stream); return(putc(i&0xff, stream)); } 198 Image Alchemy G Undercolour Removal Files ------------------------------------------------------------------- Summary Undercolour removal files are text files which control the conversion from RGB to CMYK colour space. This conversion consists of four steps. The first is to convert an RGB value to an ideal CMY value; this simply involves negating the RGB values. The next step is to determine how much black is in that colour; this is done by finding the minimum of the CMY values and using that as an index into the black removal tables documented below. These tables have independent values for how much black to use for that pixel and how much black to subtract from the CMY values. Next, a linear transform is optionally applied to the CMY portion of the CMYK pixel. Finally the CMYK values are optionally translated, independently, through the CMYK density correction tables (this last step is only used if Alchemy is going to dither the image for output on a 1 bit per pixel per component device). File format Any line beginning with ';' is a comment and is ignored. Black removal The first 256 non-comment lines contain tables undercolour removal values corresponding to computed black values of 0 (white) to 255 (black). Each of these lines has two numbers; the first indicates how much black to use in place of the computed black value corresponding to the line, and the second indicates how much black to subtract from the cyan, magenta, and yellow components (this value must not be greater than the corresponding computed black value). After the black removal block the remaining blocks may appear in any order. Image Alchemy 199 CMY linear If there is a line which says only "HSI CMY transform matrix" then the next 3 non-comment lines contain a matrix representing a linear transform which is applied to the cyan, magenta, and yellow components after black removal and before applying the density map. The entries are normalized around 256. The first row and column represent cyan, the second magenta, and the third yellow. The rows are multiplied by the input cyan, magenta, and yellow values to create the corrected values. A matrix of 256 0 0 0 256 0 0 0 256 is equivalent to omitting the matrix and causes no correction to take place. In this case it would be preferable to omit the matrix as the conversion will run slightly faster without it. CMYK density If there is a line which says only "HSI CMYK correction density map" then the next 256 non-comment lines tables contain density correction tables, corresponding to cyan, magenta, yellow, and black values of 0 (white) to 255. Each of these lines has four numbers representing, in order, the amount of cyan, magenta, yellow, and black to use in place of the corresponding computed values. These tables are only applied during dithering; they will not be used for those CMYK output formats which are continuous tone, as devices which take continuous tone input data should be doing their own correction. Example The following undercolour removal file has undercolour removal tables, CMYK density correction tables, and a CMY colour correction matrix. ; Undercolour removal file ; 0 0 1 1 1 1 2 2 3 3 ... (256 entries total) 169 169 200 Image Alchemy 169 169 170 170 ; HSI CMY matrix ;the following matrix leaves the ; Cyan and Yellow planes alone, and ; subtracts a bit from the Magenta ; plane when there's Cyan present. ; 256 0 0 -32 256 0 0 0 256 ; HSI CMYK density map ; 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 ... (256 entries total) 246 246 246 246 248 248 248 248 251 251 251 251 253 253 253 253 255 255 255 255 Image Alchemy 201 H PAL Files ------------------------------------------------------------------- Overview PAL files are text files which contain a palette in an ASCII form. Alchemy can extract palettes from other file formats and write PAL files. Alchemy can also use PAL files when converting images. File format The first line contains the letters "PAL"; this identifies the file as a palette file. The next line contains an integer indicating the number of palette entries. Valid values are 2 through 256. The rest of the file consists of lines of 3 numbers each (separated by spaces) representing the red, green, and blue values for each of the colours. These have a range of 0 (black) to 255 (full intensity). Example PAL 8 ;# colours 0 0 0 ;black 255 0 0 ;bright red 0 128 0 ;dark green 255 255 0 ;yellow 0 0 255 ;blue 255 0 255 ;magenta 63 63 63 ;gray 255 255 255 ;white 202 Image Alchemy I Acknowledgments ------------------------------------------------------------------- Summary Almost all the software which comprises Image Alchemy was written in house. However the TIFF and 640x400 SVGA display modules are modifications of software originally written by other people. Both of these modules are free for anyone's use as long as proper credit is given as to the origin of the software. TIFF Image Alchemy's TIFF I/O is based on libtiff which is copyright by Sam Leffler and is used with his permission. If you are interested in reading or writing TIFF files we strongly suggest that you start with libtiff. Libtiff is available by anonymous ftp as ucbvax.berkeley.edu:pub/tiff/*.tar.Z or uunet.uu.net:graphics/tiff.tar.Z. If you cannot get a copy of libtiff via anonymous ftp please contact us for a free copy. VGA display Image Alchemy's 640x400 SVGA display routines are based on VGAKIT, written by John Bridges. VGAKIT is available free of charge from a variety of bulletin boards If you cannot find VGAKIT locally please contact us for a free copy. Image Alchemy 203 J Other Useful Software ------------------------------------------------------------------- Summary There are several image processing packages available for little or no cost. Please be aware that we mention these software packages only as a service to Image Alchemy users. We are not endorsing or recommending any particular package. Many of the packages are not supported by their authors. If you have trouble finding any of the listed software please send us a blank tape or diskette and we will send you a copy free of charge (please be aware that the software may be quite large; contact us first if you have any questions). If you know of any other software which would be appropriate to add to this list please let us know. If you are the author of any of these packages and you would rather not be on this list please let us know. 204 Image Alchemy IBM PC PicLab A public-domain image file conversion and printing tool. Written by Lee Crocker and the Stone Soup Group. Available via CompuServe. Cshow A shareware image viewing program. Written by Bob Berry. Available from: Canyon State Systems and Software PO Box 86 Sedona, AZ 86336 Vivid A shareware ray-tracing program. Written by Stephen B. Coy Available from: Stephen Coy 15205 NE 13th Pl., #2904 Bellevue, WA 98007 Workstations These programs are only available as source code and generally require a workstation running UNIX or one of its variants. Utah Raster Written by Spencer W. Thomas, Rod G. Bogart, and Toolkit (URT) James Painter. Available via anonymous FTP as pub/urt-3.0.tar.Z via anonymous ftp from cs.utah.edu, weedeater.math.yale.edu, or freebie.engin.umich.edu. Fuzzy Bitmap Written by Michael Mauldin Manipulation Available by anonymous ftp as (FBM) nl.cs.cmu.edu:/usr/mlm/ftp/fbm.tar.Z, uunet.uu.net:pub/fbm.tar.Z, or ucsd.edu:graphics/fbm.tar.Z. Portable BitMap Written by Jef Poskanzer (PBMPLUS) Available by anonymous ftp as expo.lcs.mit.edu:contrib/pbmplus.tar.Z or ftp.ee.lbl.gov:pbmplus.tar.Z. Image Alchemy 205 Img Software Written by Paul Raveling Set Available by anonymous ftp as expo.lcs.mit.edu:contrib/img_1.3.tar.Z or venera.isi.edu:pub/img_1.3.tar.Z. 206 Image Alchemy Glossary ------------------------------------------------------------------- Anonymous FTP An easy way to transfer files via the Internet. If you don't have Internet access you can't use anonymous FTP; if you do have Internet access you probably already know about it (if you don't, ask your system administrator or local network guru). Black and white An image which contains just two colours, black and white. Many file formats, such as TIFF and Sun Raster, have special variations for black and white images. You can force Alchemy to write a black and white image by specifying -b -c2 as options. Dithering A technique for reducing the amount of colour banding in an image when converting from a large number of different colours to a small number of different colours. Different dithering techniques are usually named after the person or persons who first invented them. Alchemy supports Floyd- Steinberg, Stucki, and JJN dithering; these are further described in "Digital Halftoning", by Robert Ulichney, MIT Press. Gray-scale An image which contains just shades of gray. Many file formats, such as TIFF and Silicon Graphics, have special variations for gray-scale images. You can force Alchemy to write a gray-scale image by specifying -b -8 as options. Header The portion of an image file that is not the actual image data. The data in a header generally includes the image size (in pixels), the image depth (in number of bits per pixel or number of colours), and the palette (if the image has a palette). Some file formats include quite a bit of additional data in the header, such as: the name of the image, the date and time the image was created, and the latitude and longitude of the image (primarily used by satellite image data). The header is called the header because it usually appears at the head of the file. Some file formats store information which is usually found in the header in a separate file. Image Alchemy 207 Heckbert colour A technique for reducing the number of colours quantization needed by an image, typically used to convert a true colour image to a paletted image. Named after Paul Heckbert who originally described the technique in "Color Image Quantization for Frame Buffer Display", SIGGRAPH '82 Proceedings, p. 297. Magic Number A number or sequence of numbers that is found at or near the start of an image file so that software may determine what type of format the file is. Most formats have a well defined magic number; some formats do not, in which case Alchemy examines various parameters in the header of the file and guesses what format the image is. Paletted An image which isn't true colour. Each pixel in the image is an index into a table of values (typically red, green, and blue) which describe the colour of that pixel. Most paletted images are limited to 8 bits of information, which allows 256 unique colours. Most display adapters only allow the display of paletted images (Alchemy can display true colour images on those display adapters by using a uniform palette). True colour An image which does not contain a palette. Each pixel in the image is represented by at least three values, typically red, green, and blue. True colour images are generally produced by scanners and digitizers and are better quality and much larger than paletted images. Most display systems cannot display true colour images. 208 Image Alchemy References ------------------------------------------------------------------- General Computer Graphics - Principles and Practice, Computer Second Edition Graphics (Commonly referred to as Foley and van Dam) J.D. Foley, A. van Dam, S.K. Feiner, and J.F. Hughes Addison-Wesley ISBN 0-201-12110-7 Principles of Interactive Computer Graphics (Commonly referred to as Newman and Sproull) W.M. Newman and R.F. Sproull McGraw-Hill ISBN 0-07-046338-7 Algorithms for Graphics and Image Processing Theo Pavlidis Computer Science Press ISBN 0-914894-65-X Graphics Gems Andrew S. Glassner Academic Press ISBN 0-12-286165-5 Graphics Gems II James Arvo Academic Press ISBN 0-12-064480-0 Bit-Mapped Graphics Steve Rimmer Windcrest ISBN 0-8306-3558-0 Image Alchemy 209 Specific Topics Colour The Reproduction of Colour in Photography, Printing & Television R.W.G. Hunt Fountain Press ISBN 0 85242 356 X Dithering Digital Halftoning Robert Ulichney MIT Press. ISBN 0-262-21009-6 Image Scaling Digital Image Warping George Wolberg IEEE Computer Society Press Monograph ISBN 0-8186-8944-7 VGA Programming Programmer's Guide to the EGA and VGA Cards, Second Edition Richard F. Ferraro Addison-Wesley ISBN 0-201-57025-4 210 Image Alchemy