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Image Alchemy
Version 1.6
Addendum
Handmade Software, Inc.
Trademarks Image Alchemy is a trademark of Handmade
Software, Inc.
All other products or services mentioned in this
manual 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.
Copyright (c) 1990-1992 Handmade Software, Inc.
All Rights Reserved
First Printing
Handmade Software, Inc.
15951 Los Gatos Blvd., Suite 17
Los Gatos, CA 95032
+1 408 358-1292
+1 408 358-2694 fax
+1 408 356-3297 BBS
Internet: hsi@netcom.COM
CompuServe: 71330, 3136
Image Alchemy v1.6 Copyright (c) 1992 Handmade Software Inc. Addendum-ii
Contents
-----------------------------------------------------------------
Introduction.......................... 1
Image Alchemy for MS-DOS.............. 2
File Formats.......................... 4
Alpha Microsystems BMP............. 5
AVHRR.............................. 6
CALS............................... 8
Cubicomp PictureMaker.............. 9
Dr. Halo CUT...................... 10
First Publisher ART............... 11
GEM VDI Image File................ 12
GOES.............................. 14
IBM Picture Maker................. 16
PDS............................... 17
RIX............................... 18
SGI............................... 19
SPOT Image........................ 20
Sun Raster........................ 21
Windows Bitmap.................... 22
XPM............................... 25
Colour and Palette Options........... 26
Dither............................ 27
Gamma correction.................. 29
Negate............................ 31
Spiff............................. 32
Viewing Options (MS-DOS Only)........ 34
View Image in 15 Bit Mode......... 35
View Scaled Image in 15 Bit Mode.. 36
Answers to Frequently Asked Questions 37
Version History...................... 38
Image Alchemy v1.6 Copyright (c) 1992 Handmade Software Inc. Addendum-iii
Introduction to this Addendum
-----------------------------------------------------------------
Why an Addendum? This addendum covers changes in Image Alchemy
that were made after the manual was printed.
These changes consist of new file formats,
changes to existing file formats, additions and
changes in colouring options, and changes in the
viewing options (for the MS-DOS version only).
Where changes have been made, this manual covers
the options in their entirety, saving you the
trouble of having to look at both manuals for a
single option.
Image Alchemy v1.6 Copyright (c) 1992 Handmade Software Inc. Addendum-1
Image Alchemy for MS-DOS
-----------------------------------------------------------------
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).
It is possible for there to be some
incompatibility when using some older drivers
and/or TSRs which also use extended memory.
Therefore Alchemy's use of extended/expanded
memory can be disabled. To disable 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, just speed up conversions. We
also have a 386 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 Alchemy/386.
Checking for Alchemy will normally check to determine if
8514/A boards there 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 v1.6 Copyright (c) 1992 Handmade Software Inc. Addendum-2
Limiting maximum Alchemy will automatically choose the lowest
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 all the resolutions the
SVGA board does. Therefore 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, "set alchemy=800",
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".
Image Alchemy v1.6 Copyright (c) 1992 Handmade Software Inc. Addendum-3
Output Options
-----------------------------------------------------------------
Introduction Since the release of v1.5 several new output
formats have been added and several existing
output formats have had compression modes or
output options added.
Formats which have had options added:
GEM VDI Sun Raster
SGI Windows BMP
New formats:
Alpha Microsystems BMP
AVHRR
CALS
Cubicomp PictureMaker
Dr. Halo CUT
First Publisher ART
GOES
IBM Picture Maker
PDS
RIX
SPOT Image
XPM
In addition to those changes, the following
formats are now optimally compressed when they
are written by Image Alchemy; this can result in
a significant savings in disk space for certain
images:
WPG
Utah Raster Toolkit (RLE)
GEM IMG
Image Alchemy v1.6 Copyright (c) 1992 Handmade Software Inc. Addendum-4
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 v1.6 Copyright (c) 1992 Handmade Software Inc. Addendum-5
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
Creator 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 v1.6 Copyright (c) 1992 Handmade Software Inc. Addendum-6
Examples Convert the GOES file, florida.goe, to an
uncompressed IDIDAS AVHRR file:
alchemy --R1 florida.goe
Image Alchemy v1.6 Copyright (c) 1992 Handmade Software Inc. Addendum-7
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.
Examples Convert the TIFF file page1.tif to a CALS file:
alchemy page1.tif --c
Image Alchemy v1.6 Copyright (c) 1992 Handmade Software Inc. Addendum-8
Cubicomp PictureMaker --P
Cubicomp PictureMaker files are used in
broadcast-quality three dimensional modelling
and animation.
Syntax --P
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.
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.
Examples Convert the 24-bit JPEG image stones.jpg to
PictureMaker files:
alchemy --P stones.jpg
Image Alchemy v1.6 Copyright (c) 1992 Handmade Software Inc. Addendum-9
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 v1.6 Copyright (c) 1992 Handmade Software Inc. Addendum-10
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
Image Alchemy v1.6 Copyright (c) 1992 Handmade Software Inc. Addendum-11
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:
alchemy -c 8 --g bigscan.tga -X640
-Y480 -d2
Image Alchemy v1.6 Copyright (c) 1992 Handmade Software Inc. Addendum-12
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 v1.6 Copyright (c) 1992 Handmade Software Inc. Addendum-13
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
Creator 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.
Image Alchemy v1.6 Copyright (c) 1992 Handmade Software Inc. Addendum-14
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 images 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 v1.6 Copyright (c) 1992 Handmade Software Inc. Addendum-15
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 can not 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
Image Alchemy v1.6 Copyright (c) 1992 Handmade Software Inc. Addendum-16
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
Image Alchemy v1.6 Copyright (c) 1992 Handmade Software Inc. Addendum-17
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 v1.6 Copyright (c) 1992 Handmade Software Inc. Addendum-18
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 -.
Image Alchemy v1.6 Copyright (c) 1992 Handmade Software Inc. Addendum-19
SPOT Image --S
SPOT Image GIS data files are high-resolution
satellite images produced by SPOT Image
Corporation.
Syntax --S
Extensions .hdr (For image header information)
.bil (For pixel data)
.clr (For palette data [optional])
Creator SPOT Image Corp.
Used by SPOT Image Corp.
Variations 8 bits per pixel
Limitations Only 1 band, GIS images are supported; if you
have any other type of SPOT GIS images we would
be interested in supporting them, please contact
us.
Comments SPOT Image 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.
Examples Convert the Erdas file, phoenix.lan, to a SPOT
Image file:
alchemy --S phoenix.lan
Image Alchemy v1.6 Copyright (c) 1992 Handmade Software Inc. Addendum-20
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 v1.6 Copyright (c) 1992 Handmade Software Inc. Addendum-21
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.
Image Alchemy v1.6 Copyright (c) 1992 Handmade Software Inc. Addendum-22
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 an image with a palette
identity file 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
Image Alchemy v1.6 Copyright (c) 1992 Handmade Software Inc. Addendum-23
Convert the image test.gif to an icon file for
use with Windows 3.1:
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
Image Alchemy v1.6 Copyright (c) 1992 Handmade Software Inc. Addendum-24
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
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 can not read
please contact us.
Some XPM files contain colour names instead of
colour values for some of the colours. The
conversion table of these names into values is
in the file rgb.txt. Alchemy will look for this
table in the current directory and automatically
use it to convert XPM files if it is needed.
Therefore you may have to copy the rgb.txt file
to the current directory (its location is system
dependent; ask you system administrator if you
need help finding it).
Comments When writing an XPM file with less than 27
colours Alchemy writes 1 character XPM files,
otherwise Alchemy writes 2 character 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
Image Alchemy v1.6 Copyright (c) 1992 Handmade Software Inc. Addendum-25
Colour and Palette Options
-----------------------------------------------------------------
Introduction Since version 1.5 we have added two options to
the colour and palette section:
Image Negation
Gamma Correction
Also the options for these options has been
expanded:
Dithering
Spiffing
Image Alchemy v1.6 Copyright (c) 1992 Handmade Software Inc. Addendum-26
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)
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.
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.
Image Alchemy v1.6 Copyright (c) 1992 Handmade Software Inc. Addendum-27
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
and 21.
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 and 21.
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
Image Alchemy v1.6 Copyright (c) 1992 Handmade Software Inc. Addendum-28
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 v1.6 Copyright (c) 1992 Handmade Software Inc. Addendum-29
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
Image Alchemy v1.6 Copyright (c) 1992 Handmade Software Inc. Addendum-30
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
Image Alchemy v1.6 Copyright (c) 1992 Handmade Software Inc. Addendum-31
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
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.
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.
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
Image Alchemy v1.6 Copyright (c) 1992 Handmade Software Inc. Addendum-32
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 v1.6 Copyright (c) 1992 Handmade Software Inc. Addendum-33
Viewing Options (MS-DOS Only)
-----------------------------------------------------------------
Display hardware Image Alchemy v1.6 supports VESA compatible and
S3 equipped SVGA boards for 15 bit viewing. In
addition, a scaled 15 bit viewing option has
been added.
There are also two new environment variable
options which affect viewing. One allows the
disabling of checking for the 8514/A board
(which causes problems with some network adapter
boards) and the other allows you to specify the
maximum resolution that your monitor is capable
of when viewing with a VESA compatible VGA
board; see the section on installing Image
Alchemy earlier in this addendum.
Image Alchemy v1.6 Copyright (c) 1992 Handmade Software Inc. Addendum-34
View Image in 15 Bit Mode --v
Purpose View file using 15 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 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.
24 bit images will be dithered to 15 bit when
using this option. You can turn off dithering
(speeding up the display and slightly reducing
the image quality) by using the -d option.
Related options --V View scaled image in 15 bit mode
-d Specify dither type
Example View madonna.tga:
alchemy madonna.tga --v
Image Alchemy v1.6 Copyright (c) 1992 Handmade Software Inc. Addendum-35
View Scaled Image in 15 Bit 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 v1.6 Copyright (c) 1992 Handmade Software Inc. Addendum-36
Answers to Frequently Asked Questions
-----------------------------------------------------------------
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
Image Alchemy v1.6 Copyright (c) 1992 Handmade Software Inc. Addendum-37
Version History
-----------------------------------------------------------------
Version 1.6 Released for MS-DOS, 80386 Protected Mode, Sun
05/92 SPARC, Interactive UNIX, SCO UNIX, IBM RS/6000,
HP 9000/7xx & 8xx, and Silicon Graphics IRIS.
Format Added AVHRR support.
Added PDS support.
Added RIX support.
Added SPOT Image support.
Added GOES support.
Added CALS support.
Added Alpha Microsystems BMP support.
Added Dr. Halo CUT support.
Added First Publisher ART support.
Added PictureMaker support.
Added XPM support.
Added IBM Picture Maker support.
Disabled LZW Compression in TIFF pending
resolution of patent issues (and changed default
TIFF compression to PackBits).
Added support for reading tiled TIFF images.
Added support for reading JTIFF images.
Added support for several additional types of
incorrect TIFF files.
Added support for reading type 1, mapped PICT
files.
Added support for reading and writing multi-bit
grayscale and colour GEM files.
Added support for reading 4 bit XWD files.
Added support for an additional type of
incorrect Targa file.
Made PCL reading more robust (including adding
support for landscape files).
Added support for reading old format BMP files.
Added support for Gamma information in Utah RLE
files.
Added default palettes to WPG reading.
Added support for reading 5-5-5 PICT files.
Added compression option to Sun Raster and SGI
files.
Added compression to writing Utah RLE, GEM, and
WPG files.
Added support for writing BMP Icon files and BMP
palette identity files.
Image Alchemy v1.6 Copyright (c) 1992 Handmade Software Inc. Addendum-38
Display Added support for 15 bit VESA compatible SVGA
(MS-DOS) boards.
Added support for S3 equipped 15 bit SVGA
boards.
Added scaled 15 bit view option.
Added environment variables to indicate monitor
resolution.
Misc Decreased memory usage for MS-DOS version
(allowing the conversion of larger images).
Added 5 new dithering types.
Added histogram equalization option to spiff.
Added negative flag.
Added gamma correction.
Bugs fixed Writing to directories not on the current disk
(MS-DOS).
Reading certain 1 bit PCX files.
Reading certain PICT files.
Checking for Targa files.
Viewing on certain VESA boards (MS-DOS).
Reading certain 8 bit ILBM files.
Scaled viewing of very skinny images (MS-DOS).
Histogram equalization (non MS-DOS).
Writing WPG files.
Writing 1 bit PBM files.
Image Alchemy v1.6 Copyright (c) 1992 Handmade Software Inc. Addendum-39
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