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Text File | 1991-11-04 | 68KB | 1,545 lines

////////////////////////////////////////////////////// /////////// // /// //// ///// // / /////// ////////// / / / //// //// ///// / /////////// ///////// / / //// //// / / / ////////// //////// / / / / / //// // / / ///////////// /////// // / // ////// // / ////////////// ////////////////////////////////////////////////////// Version 3.0 by Damien M. Jones October 31, 1991 DMJ GIF Program and Manual Copyright © 1991 Damien M. Jones. All Rights Reserved. Page 2 Copyright Notice DMJ GIF, its companion utilities, and this manual are all Copyright 1991 Damien M. Jones, All Rights Reserved. You may copy unregistered versions of the program as you wish as long as all of the files listed in the file READTHIS.1ST are included. You may not charge for these copies, except reasonable charges to cover the acquisition of the program and the media it is distributed on (as in Public Domain/Shareware distributors). This charge should not exceed $10. Registered copies of DMJ GIF should not be copied except for your own personal use. The rule of thumb here is multiple copies on one computer, or one copy on multiple computers (although not simultaneously). You may sell your registered copy of DMJ GIF, but your printed manual must accompany the sale, and new owners should send their program disk back to register the change of ownership, or they will not receive updates. Shareware Notice This program is Shareware. If you like it and use it, please send $15 to the address on the front cover. In return for registering this program, you will receive a printed manual and the latest registered version of DMJ GIF. Registered versions of DMJ GIF are almost twice as fast as unregistered versions, and are not to be distributed. You'll also receive free updates to the program as they become available. About this Manual If you've used DMJ GIF before, you'll notice that this is a new manual. You should be able to skip the introduction, but be sure to read the rest of the manual before trying to use DMJ GIF. It's a completely different program now; you'll be in for a surprise or two. This text for this manual was created with ST Writer Elite 4.2. About the Programs The programs DMJ GIF, SPC2PI1, SPC2PI3, SPU2SPC, and SPC-3375 were all written in GFA BASIC 3.07, with portions written in assembly. The code is entirely mine, except for the Spectrum display and decompression routines. Thanks to Trio for writing those two and releasing them to the public. Page 3 Table of Contents Introduction . . . . . . . . . 4 Running DMJ GIF . . . . . . . 5 The Main Dialog . . . . . . . . 5 Converting a GIF . . . . . . . 6 The Custom Fileselector . . . . . . 8 Batch Conversions . . . . . . . 11 ST Resolution GIFs . . . . . . . 13 Conversion Types . . . . . . . 13 Dithering . . . . . . . . . 14 Palettes . . . . . . . . . 14 Scaling . . . . . . . . . . 15 Mapping . . . . . . . . . 16 Interlaced GIFs . . . . . . . . 18 Keyboard Shortcuts . . . . . . . 18 Preferences . . . . . . . . . 19 Bugs . . . . . . . . . . 20 Feedback . . . . . . . . . . 21 The Companion Utilities . . . . . 21 Thanks... . . . . . . . . . 23 Page 4 Introduction Great. You've managed to get your hands on DMJ GIF, undoubtedly the best non-commercial GIF to Spectrum converter available. This program also allows you to convert entire batches of GIF's at once, without your supervision. It allows you to convert to Spectrum, DEGAS, or Tiny, in color, grey scale, or monochrome, using either the ST's regular palette or the STe's enhanced palette, converting ANY size GIF--and it runs in only a half meg. If you don't know what a GIF file is, well, it's a picture format developed by CompuServe as a sort of standard. Since many different computers can create and use pictures in this format, and because of the efficient compression used to save space, this is an ideal format for exchanging pictures via bulletin board systems. It doesn't matter what kind of computer the picture was created on, because the GIF standard doesn't care. Neither does your ST. Well, not too much, that is. The ST has three different graphics resolutions it can use. There is low resolution, which is 320x200x16; there's medium resolution, which is 640x200x4; and there is high resolution, which is 640x400 in monochrome. The problem arises in that most GIF pictures don't fit nicely into one of the ST's resolutions. A lot of them are 640x350x16, or 320x200x32, or 640x480x256. And while the ST has 512 colors it can choose from (the palette size), most GIF pictures use a much larger palette--allowing them much greater detail in colors. A few years ago, some very, very clever programmers devised a way to put all 512 of the ST's colors on the screen at one time. So they effectively added a fourth graphics resolution to the ST: Spectrum mode, or 320x200x512. Although the pixel resolution is the same as low resolution, and the palette size is still only 512 colors, these colors can be mixed, or "dithered", to make it look like there are a lot more on the screen. This wouldn't be possible unless there were fewer restrictions on using colors; 16 colors just isn't enough to do the dithering that DMJ GIF does. DMJ GIF is not the first program that converts GIF pictures to Spectrum pictures. But this program excels in its handling of pictures that are larger than the ST's low resolution of 320x200. Here's why: most programs (or should I say, every single program I've ever used except the Spectrum paint program itself) don't scale things very well. Let's say, for example, that you want to convert a picture that's 640x400x16 colors down to a picture that's 320x200x512. What you'd do is divide the entire screen up into little squares--each square being 2x2 pixels. Most programs look at each little square and pick one of the points, assuming it best represents the entire square. Page 5 That's usually no problem, but if you've got a lot of patterns and "dithering", then you DO have a problem, because you're leaving out 75% of the detail while preserving the other 25%. What you end up with is usually a mess. This program takes a different approach. Instead of just picking one pixel from that 2x2 square, it determines the overall color by averaging the colors of the pixels. (That's why you need 512 colors--when you start averaging 16 colors with different amounts of each one, the number of colors gets big, fast.) Of course, with fantastic results there comes a price. The price with this program is speed. Because of the averaging and the floating point (read "slow") arithmetic, this program takes a while to run. But the results are WELL worth the wait. And registered versions of DMJ GIF are much faster. Running DMJ GIF To run DMJ GIF, all you have to do is double-click on DMJ_GIF.TOS from the Desktop in medium resolution. You'll need at least 340K free; if you have only 512K I'd strongly suggest stripping out all your accessories and AUTO folder programs, since the more memory DMJ GIF has, the better it works. And even when you do this, you won't be able to convert a GIF directly to DEGAS/Tiny format in full color with only 512K, since this direct conversion uses a 96K buffer... Once you have the program loaded, you'll see a small dialog telling you this program is an unregistered version of the program. If you get a dialog thanking you for registering the program, and you haven't, then you have a pirate copy of the registered version. Please destroy it immediately! The Main Dialog The first rule of thumb when using DMJ GIF is not to freak when you see the main dialog. There's a lot of things there; DMJ GIF is a powerful program, and there's no easy way of putting all of that power at your fingertips and yet making a program easy to use. Fortunately, however, help is always at your fingertips--just press the HELP key on your ST's keyboard, and you'll receive complete help without ever leaving the program. (You will need the file DMJ_GIF3.HLP in the same folder as DMJ GIF, however; see above.) The dialog is divided into five main sections. These are "Stuff", "Files", "Control", "Options", and "Info". In the "Stuff" section you will find three buttons, "Help", "Info", and "Quit". "Help" will allow you to enter the help system; it has the same effect as pressing the HELP key. "Info" Page 6 brings up some information about the program, such as version, date, and who the program is registered to. "Quit" is used to exit the program; you will be asked if you are sure. In the "Files" box you will see space for two filenames. One is "From", which is the source file, and the other is "To", which is the destination file. In the "Control" box are the buttons that tell DMJ GIF what you want done. The buttons here are "Begin", "Add", "Remove", "Save", and "View". You'll also see a space labeled "Pictures"; this tells you how many pictures DMJ GIF has stored in its batch list. Beneath that you will see a slider, which lets you move to any picture in the list. In the "Options" box are all the settings on how to convert a GIF. You'll find five "Dither" buttons, four "Palette" buttons, and also "Map", "Guess", "Exact", "Type", "Skip", and "Prefs". In the "Info" box you'll see blanks for "Image Size", "Palette Size", and "Colors". You'll also see a button labeled "More", which brings up a lot more information about the current picture. Converting a GIF Despite appearances (that main dialog can be quite intimidating) converting a GIF is not actually that difficult. To begin with, you need to tell DMJ GIF just what file you want to convert. So grab the mouse and click on the "From" filename in the upper right hand corner of the dialog. A file selector will appear, allowing you to choose a GIF file. (If you have trouble with the custom file selector, you can either press HELP, or read the section below on the custom file selector.) Just choose the GIF picture you want to convert, and then click on "Okay". You'll then see a small status display in the center of the screen, tell you it is "Analyzing" a file. This just means DMJ GIF is looking at the GIF to find out how it should convert it. For most pictures this is reasonably fast; for 256-color VGA pictures it takes about eight seconds. That step completed, you will find several things have happened: first, the "To" file has been changed to almost the same as the "From"--the only difference being the last three letters. This is called the extension. For a GIF picture, the extension is "GIF"; for a Spectrum picture, it's "SPC" or "SPU". "SPC" is compressed form, which saves disk space. "SPU" is uncompressed form. Another change is that the blanks in the "Info" area have Page 7 suddenly been filled. Don't worry about that now; that information just describes the GIF picture you've selected. The last change is that one of the "Dither" buttons in the "Options" section has been selected, as has one of the "Current Palette" buttons. Don't worry about that yet either. All you have to do now is select the "Begin" button in the "Control" section of the dialog. DMJ GIF will begin converting the picture from GIF format to Spectrum format. This can take some time, so don't panic when it isn't finished in the blink of an eye. When the entire conversion is done, DMJ GIF will save the picture to the disk. While DMJ GIF is busy, you'll see a small status display in the middle of the screen. It will tell you what DMJ GIF is doing, and approximately how much of that task it has already completed. "Analyzing" refers to two things: first, when a GIF is first read, its palette must be analyzed to determine the proper amount of dithering. Second, it refers to analyzing the colors of a converted picture to determine which colors to use. "Reading" refers to the simple task of loading the picture from the disk. "Uncompressing" refers to the task of uncompressing a picture. For most GIFs this is done during "Scaling", but interlaced GIFs must be uncompressed first; Mapped pictures must also be partially uncompressed. ST format pictures (Spectrum, Tiny, and DEGAS Elite) must also be uncompressed before being viewed. "Scaling" refers to the time-consuming process of reducing and averaging the picture to the proper size. "Plotting" refers to the actual process of plotting the picture; this is usually done at the same time as "Scaling". "Compressing" refers to the task of compressing the picture prior to saving it, and "Writing" refers to the actual saving to disk of the picture. Note that not all of these steps need appear for any single picture; usually all you'll see during the actual conversion are "Reading", "Scaling", "Compressing", and "Writing". You can abort the conversion at any time by pressing any key; a small dialog will appear, giving you three choices. The first one, "Abort", will end the conversion and return you to the main dialog. The second option, "Peek", will allow you to look at the picture--at least, as much of it as has been converted. Press any key to return to the conversion. The last option, "Cancel", will simply return you to the conversion. (If the "Peek" option does not appear, that's because the picture is not yet in ST displayable form. You can "Peek" at any picture while it is in the "Scaling" phase, except Full Color conversions to Low Resolution (non-Spectrum), in which case you must wait for the "Plotting" phase.) Page 8 See? That wasn't so hard. All of those other options--reduction factors, dithering, and filename--are automatically selected by DMJ GIF. Most of the time you won't have to worry about any of them. About the only one you might want to change is the "Destination" file. All you have to do to change that is to click on it, and a file selector will appear, allowing you to choose the name for the destination file. Remember that this should end in either ".SPC" (for a compressed picture) or ".SPU" (for an uncompressed picture). If it doesn't, DMJ GIF will restore the extension you previously had. (If you're not converting to a Spectrum picture, then you won't be using ".SPC" or ".SPU" as the extension. See "Conversion Types" for more information.) The Custom Fileselector DMJ GIF uses a custom file selector. It's really quite simple to use. If you have an alternate file selector loaded (like the Universal Item Selector, or the Little Green Selector) you won't be able to use it. At the top of the file selector is a line of text telling you what file you're supposed to be selecting with the file selector. By "grabbing" this bar with the mouse (i.e. move the pointer to it, press, and hold the left button down) you can drag the entire file selector to a new spot on the screen. The file selector will appear at this same spot every time you use it, until you leave the program. Below this line, you will see a line of text containing the pathname. You cannot change this line directly. More on this later. Below the pathname is the major component of the file selector: the filenames. This large white box contains up to 24 filenames at a time. To select a filename, just click on it. Then click on the "Okay" button, which you will find in the lower right hand corner of the file selector. You can also just double-click on the filename and skip clicking on the "Okay" button; it will do the same thing. Below the white filename box you will see the name of the currently selected file. This filename can be edited with the keyboard. You can use the left and right arrow keys, BACKSPACE, and DELETE to edit this filename. You will not be able to enter an illegal filename. You can press ESC to erase the filename completely; CTRL and the left or right arrow key will move the cursor to the beginning and end of the filename, respectively. In the lower right hand corner of the file selector you will find two buttons, "Okay" and "Cancel". Selecting "Okay" Page 9 confirms the choice listed in the "Filename" area in the lower left hand corner of the file selector. Selecting "Cancel" aborts this selection process. Pressing RETURN on the keyboard is the same as selecting "Okay"; pressing UNDO is the same as selecting "Cancel". Directly to the right of the white filename box is a vertical slider. This is only useful when there are more than 24 files in the current folder. You can use the up and down arrow buttons to scroll the names; you can click above or below the slider itself to move the slider in that direction quickly; or you can drag the slider to a new position directly. You may have noticed some of the files in the white filename box have a small > symbol to their left. These aren't files; they are folders. You can click on a folder's name (just once) to change the current folder and see what's inside it. The pathname line directly above the white filename box will reflect the change--the new folder name will be added on the end. To exit back out of the folder, you can either select the "<-" button in the upper right hand corner of the file selector, or click on the part of the pathname that you want to go to. For example, if your current folder is "D:\PICTURES\GIF\" and you wanted to go back to the PICTURES folder, you could either select the "<-" button, or click on the word "PICTURES" in the pathname line. You can jump back several folders at a time with just one click. In the example above, you could click on "D:\" and go to the main directory of the disk, whereas it would take two clicks of the "<-" button to do the same. There are three other buttons in the upper right hand corner of the file selector. One has a drive letter on it; another has a disk icon on it; the third has "*.*" on it. The drive letter button allows you to quickly change the current drive. Just click and hold the mouse button down on the drive letter. Move the mouse pointer to the drive you want to use, and release the mouse button. You will not be able to select a drive that does not exist--this also means drive B:, so if you have a single floppy drive, forget about drive B:. The disk icon button serves no other purpose but to tell the file selector that you have inserted another disk, and you would like to reread the disk's directory. The "*.*" icon, however, will require some explanation. This button calls up another dialog that allows you to select the "search mask". The search mask is how you tell the file selector which files you want to see in the white filename box. You shouldn't normally need to use this. Before explaining about the search mask dialog, a little explanation about search masks themselves is necessary. Search masks are just filenames with wildcards in them. There are two Page 10 wildcard characters that are used: the asterisk (*) and the question mark (?). The question mark represents any letter--but only one letter. The asterisk represents any number of letters. Here's some examples to make things clearer: the wildcard PIC?.SPC would match PIC1.SPC, PIC2.SPC, and PICZ.SPC, but not PIX1.SPC, PIC.SPC, or PIC23.SPC. The wildcard PIC*.SPC would match PIC1.SPC, PIC2.SPC, PICZ.SPC, PIC.SPC, PIC23.SPC, and PICTURE.SPC, but not PIX1.SPC or PIXELS.SPC. See? That's why the wildcard "*.*" is used to mean all files--because it matches all filenames. Any number of characters, of any type, match the first *. Then there's the period, which separates the name from the extension. The last * matches any extension, no matter how long it is. The catch here is that GEMDOS takes a shortcut when it comes to "*.*". That wildcard shouldn't match the filename "TEST", because it doesn't have a period in it. But because GEM doesn't actually record the period on the disk, it assumes it is there. So when GEMDOS checks for files, "TEST" comes out to be "TEST.", and so fits the wildcard. You've undoubtedly used wildcards before. In the GEM File Selector, the wildcard appears at the end of the pathname. Many programs make use of wildcards to mask out files you don't need to worry about. For example, when selecting a picture from SPC-3375, it uses a search mask of *.SP?. This allows all files to appear in the GEM File Selector, as long as the first two letters of the extension are "SP". So anything with an extension of "SPC" and "SPU" will show up. Unfortunately, anything with an extension of "SPX" or "SPQ" will also show up. It would be nice if there was an easy way to allow only the extensions "SPC" and "SPU". The DMJ GIF file selector allows you to do just that. It allows you to take several wildcards and chain them together to make one mask; a file only needs to fill one of the wildcards to appear in the white filename box. You separate wildcards with the vertical bar character, |. So to display just Spectrum pictures, you'd use the mask "*.SPC|*.SPU", instead of the less precise "*.SP?". Now that the enhanced wildcards have been explained, I can explain how to use the "*.*" dialog. You will see ten lines in the dialog, each with a different search mask. To select one of these search masks, just select its button, which can be found at the left side of the dialog. You can select "Ok" to confirm your choice, or double-click on your choice to avoid the "Ok" button. You can press F1-F10 in place of click on the selection buttons, and you can press RETURN in place of clicking on the "Ok" button. If you want to change one of the search masks, click on the mask you want to change. Then use the arrow keys, BACKSPACE, and DELETE to edit the search mask on that line. Remember that simply editing a mask does not select it; you must choose its button Page 11 on the left hand side. Also note that you cannot edit the top two lines. These are reserved. The top line has the mask provided when the fileselector was called up; the second line has the catch-all "*.*". This file selector is new and different, yes. But once you learn how to use it (and it won't take very long at all) you won't even notice it. You'll find this selector appearing in more dmj software programs in the future, so you won't have to learn a new file selector for my other programs. Batch Conversions DMJ GIF does not have a separate "batch" mode; every time you convert a single picture, you are actually converting a batch of pictures, even though it is only one picture. If you want to convert a group of pictures, there are two ways to do it. One way is to select a wildcard for the "From" file, like "*.*"; this will read every GIF in the selected folder. Another way is to use the "Add" button; you can then add single files or more wildcards, even in separate folders and separate drives. DMJ GIF keeps its picture list in alphabetical order, including the entire pathname. So pictures on drive A are sorted before pictures on drive C. Once you have more than one picture in the list, you'll see the slider in the "Control" box change. You can click on the arrows next to the slider to move forward and backward through the list, or you can drag the slider to a new location. Each picture has its own dither, palette, and scaling settings, and its own destination file. If you click on the "To" filename and change the folder to save the picture in, an alert box will pop up asking you if you want to change the folders of the other pictures. "All" will change the folders of all the pictures to the same as the one you just selected; "Match" will change only those pictures that have the same path as the current picture before it was changed. "None" will change the path of none of the other pictures. Perhaps an example will make this clearer. Let's say you have three pictures, BEARS.GIF, COBRA.GIF, and EAGLE.GIF, in the folder ANIMALS. You also have the pictures MAC2RAY.GIF and MUSEUM.GIF in the folder RAYTRACE. The default "To" name for each of these pictures will be in the same folder as the picture--ANIMALS\BEARS.GIF will be saved as ANIMALS\BEARS.SPC, and RAYTRACE\MAC2RAY.GIF will be saved as RAYTRACE\MAC2RAY.SPC. Let's say you want to save all of the ANIMALS pictures in another folder called NEWSTUFF. To do that, click on the "To" name for one of the animals pictures, say, BEARS.GIF. Move to the folder NEWSTUFF instead of ANIMALS; then click on "Okay". Now the "To" name is Page 12 NEWSTUFF\BEARS.SPC. The alert box will appear, asking you if you want to change "All", "Match", or "None". Select "Match", and all the other ANIMALS pictures will be changed to the NEWSTUFF folder. Simple, huh? If you'd chosen "All", then all of the pictures (including the RAYTRACE ones) would be saved in the NEWSTUFF folder. "None" would save only BEARS.SPC in the NEWSTUFF folder, since you had already changed that one. Besides "Begin" and "Add", you'll see three other buttons in the "Control" section of the dialog. These are "Remove", "Save", and "View". "View" brings up a dialog, asking if you want to view a single picture or the entire batch list. If you select "Single" then a fileselector will appear, allowing you to choose a single picture to view. Press any key to return to the fileselector; select "Cancel" from the fileselector to end viewing single pictures. If you choose to view the entire batch list, DMJ GIF will try to show you the destination pictures in its batch list. That way, if you've just converted several pictures, you can quickly view them all. While viewing the pictures, use the left and right arrow keys to set the direction (backwards or forwards, respectively), Backspace to back up one picture, ESC or Undo to end the slideshow, or any other key to advance to the next picture. There is no time delay, so pictures will not advance until you decide to. If you attempt to view an STe picture while using an ST, DMJ GIF will "flicker" the colors to simulate 3,375 of the STe's 4096 colors. The "Remove" button simply removes all of the skipped pictures from the list. That way you don't even have to have them in your list. And the "Save" button saves the list as a script file. These script files should have an extension of .DGS (DMJ GIF Script). To load these script files back in, just click on the "From" filename; you'll see the .DGS files appear in the fileselector. Just select one. In the "Options" section there is a button labeled "Skip". "Skip" is a button that can be set for any of the pictures you have in the list; if it is set, DMJ GIF will not convert that picture, but will skip it. This is useful if you have a whole bunch of new pictures, and a few old pictures are in the group. You can just set the "Skip" button and DMJ GIF won't spend any more time converting them. Once you're happy with all of the options for each picture, just choose the "Begin" option, and DMJ GIF will go about its business converting the pictures. You can go watch a movie, get some sleep, or have a bite to eat. If you stop a conversion and choose "Abort" from the alert box, DMJ GIF will ask you if you want to abort the entire batch. Just choose "Yes" or "No"; "Yes" will stop the entire conversion process and return you to the main dialog, and "No" will proceed with the next picture. (DMJ GIF will not Page 13 ask you if it is already on the last picture, since that would be pointless.) A note on the "Add" button: It is possible to add a file that is already in the batch list. That way you can convert the same picture two different ways. Future versions may check for this and at least give a warning... ST Resolution GIFs Sometimes you will find a GIF that precisely fits an ST resolution. On such an occasion, DMJ GIF may suggest that you convert it to an ST resolution image, instead of a Spectrum picture. (Some images, although they fit an ST resolution, may have many similar colors in them, which would require dithering to bring those colors out. In these cases DMJ GIF will suggest you convert to a Spectrum picture.) You can tell when this happens by looking at the "To" filename after you select the "Source" GIF. If the extension is .SPC, DMJ GIF is still suggesting a Spectrum picture. But if it is .TNY, then DMJ GIF suggests an ST resolution. You can also change it to .PI1 or .PC1, the former being DEGAS uncompressed, and the latter being DEGAS Elite Compressed. DMJ GIF defaults to Tiny format because it usually gives the smallest size file. When using Mapping, you may find a situation where DMJ GIF again suggests saving as an ST resolution picture. Use similar steps to change the file format. In some cases, you'll find DMJ GIF suggests an ST resolution even when there are more colors than will fit in that resolution. That's because DMJ GIF has analyzed the palette, and determined that those colors can be accurately represented by dithering the other colors. This doesn't happen very often, though. Conversion Types In the "Options" section of the main dialog you will find an inconspicuous button labeled "Type". This seemingly innocent button hides some very powerful options. Basically, this button lets you choose what kind of conversion you want done. There are only three types of conversion currently available: Full Color, Grey Scale, and Monochrome. Full color converts the entire picture to a color image; Grey Scale converts the picture to a grey image; and Monochrome converts the picture to a monochrome image. DMJ GIF will automatically select whichever type of conversion is "best" for the GIF, but you can override it if you like. Also note that next to each button ("Full Color", Page 14 "Grey Scale", and "Monochrome") is a list of valid extensions. DMJ GIF will not allow you to use any extension for the destination file other than those listed next to the selected conversion type. Dithering "Dithering" is mixing two colors to get a third. In DMJ GIF, it specifically means the mixing of two very similar colors to make it look like a more precise shade--one that isn't possible with the ST's palette of 512 colors. DMJ GIF has five dithering modes; DMJ GIF will make its best guess as to which dither mode to use. This guess is based on which palette you have asked for (the ST's 512 or the STe's 4096), how similar the colors in the original GIF are, and how much scaling is being done on the picture. To set the dither mode you want to use, just click on one of the five dither buttons in the "Options" section of the main dialog. You want to use as little dithering as possible, since dithering has the effect of "fuzzing" edges. DMJ GIF will automatically set whichever dither mode it thinks is best for the current GIF, so you shouldn't have to set this often. Also, the more dithering you want to use, the larger the area of the color you need to be able to see the color detail. And the biggest reason to use as little dithering as possible is time. The more dithering, the more time it takes. Level 5 is the exception, because it uses a different technique than levels 1-4. Level 5 is about as fast as Level 3. But you should never use level 5 on a color conversion; it just doesn't produce very good pictures. You should only use level 5 for grey-scale conversions. If you change either the palette or the scaling factors, click on the word "Dither" and DMJ GIF will re-analyze the information and set the "best" dither mode. Palettes DMJ GIF will, if you choose, use the STe's palette of 4,096 colors. This gives you much greater precision in color, without having to use as much dithering. There are four palette buttons in the "Options" section. Two are labeled "Current Palette", and two are labeled "Default Palette". Each pair has an "ST" button and an "STe" button. The "Current Palette" buttons affect only the picture currently selected; they are set to whatever is selected in the "Default" pair when that picture is first analyzed. If you change the "Default" pair, DMJ GIF will ask you if you want to change all the pictures in the batch list. Answering Page 15 "No" to this question does not cancel your choice of default palette; it just doesn't change any pictures already analyzed. Using the STe's palette does not always bring better results. In some 256-color pictures, there is already more color than can be fit on one Spectrum line. By increasing the palette, you are only increasing the number of colors that should be on each line. This can make the "streaking" problem worse. If you get an STe picture with severe "streaking", use the ST palette. ST users are probably wondering why they would want to make an STe picture they can't see. DMJ GIF comes with a program to let you see the STe pictures on a regular ST. It is able to simulate 3,375 of the STe's 4,096 colors. DMJ GIF's "View" feature also performs this emulation. You can display STe Spectrum pictures with any Spectrum picture viewer, but you won't see the extra colors unless you're using an STe. Scaling As stated in the introduction, many GIF pictures are larger than the ST's 320x200 low resolution. This means a picture must be scaled, or reduced, to fit on the Spectrum screen. Unlike some programs that require the picture to be reduced the same amount both vertically and horizontally, DMJ GIF reduces each axis separately. And DMJ GIF does not require you to use whole numbers, like 1, 2, and 3. You can use fractional values, like 1.5 or 2.4. Here's some examples. Let's say you're converting the file that comes with DMJ GIF, EXAMPLE.GIF. This picture is 640x400. This gives an X (horizontal) reduction factor of 2, and a Y (vertical) reduction factor of 2. The reduction values are figured by taking the GIF's size and dividing it by the Spectrum picture's size. So 640/320=2, which is the X reduction factor; 400/200=2, which is the Y reduction factor. Soon you'll find a Super VGA GIF, which is 640x480. The X reduction factor in this case is still 2, but the Y reduction factor is 2.4, because 480/200=2.4. Remember that it's okay to use fractional values. I'm sure you've noticed that DMJ GIF automatically calculates the reduction factors for you. But if you convert an EGA GIF, which is 640x350, you'll notice that DMJ GIF suggests a Y reduction factor of 2. What's the deal? 350/200=1.75, not 2. The reason is that EGA pictures of the 640x350 type look stretched when a Y reduction factor of 1.75 is used. So after trying several other factors, I settled on 2 as a reasonable value. DMJ GIF recognizes some other resolutions Page 16 and also calculates "best guesses" to those pictures. Most of the time DMJ GIF suggests the best reduction factors for the GIF. But sometimes you may want to use different reduction factors (more on why in a bit). To change the factors, just move the cursor with the arrow keys until it is after the scaling factor you want to change. You can use ESC to erase the current number, and then enter a new one. (BACKSPACE and DELETE also work.) If you leave one of these factors blank, DMJ GIF will "Guess" the proper scaling factors. One reason to change the reduction factors might be if you were trying to create a special effect. But a more common reason is that the picture looks squashed, and you want to try to correct that. As stated above, a Super VGA GIF has reduction factors of 2 and 2.4. Occasionally a picture will appear squashed, because the aspect ratio is different. (The aspect ratio is the ratio between a pixel's width and its height.) If you convert a Super VGA GIF, and it appears squashed, try reduction factors of 3 and 3. This will maintain the aspect ratio, while still getting a fairly large picture. Now you're probably wondering why I didn't suggest just using 2.4 and 2.4. The reason is that when you use fractional factors, the number of colors increases dramatically, because you end up with a lot of fractional colors at the edges of solid areas. For Y factors, it's no problem, since one Spectrum line has no affect on any other. But you should try (if possible) to keep the X factors as whole numbers, since Spectrum only permits 42 colors per line, and all those fractional colors wouldn't come out properly... Here's where the "Guess" and "Exact" buttons are used. If you've changed the scaling factors and want to reset them, the "Guess" button can be used to have DMJ GIF provide its best guess at the scaling factors (the same guess as first provided). The "Exact" button provides the exact scaling factors; it bypasses the "best guess" part (so EGA 640x350 GIFs are scaled 2x1.75). Mapping This is one of the most sophisticated options in DMJ GIF. What it does is allow you to choose exactly what part of the GIF you want to convert to Spectrum format. To use Mapping, you must have first converted the picture normally. Since you wouldn't know you didn't want the whole image unless you'd already converted the picture, this shouldn't be a problem. Select the original GIF as the "From" file; then click on the "Map" button in the lower left Page 17 hand corner of the main dialog. You will be prompted to select the "Map" picture. This is the entire picture as it was originally converted. Here's an example: if you converted EXAMPLE.GIF and got EXAMPLE.SPC, then when you want to selectively convert the same picture, EXAMPLE.GIF would be the "Source", and EXAMPLE.SPC would be the "Map". It is extremely important that you used the reduction factors suggested by DMJ GIF in this "Map" picture, or you won't get the part you expected to get! Once you've selected the Map picture, you'll see it appear on the screen. (If you selected a Spectrum picture as the Map, DMJ GIF will first convert it to a grey scale image. This takes about ninety seconds.) Now you'll see some crosshairs on the screen. What you must do now is select the portion of the picture you want to convert. Move the crosshairs with the mouse to one corner of the part you want, and click the left mouse button. Then move the crosshairs to the opposite corner and press the left mouse button. The portion of the picture that is enclosed in the rectangle between the crosshairs is what will appear in the final picture. If you press the right mouse button after selecting one corner point, that corner point will disappear, allowing you to choose it again. If you press the right mouse button with no corner points selected, you will abort the Mapping procedure. After selecting the portion of the GIF you want to convert, you will be presented with a dialog containing two options. The first is "Same Aspect". If this is set, DMJ GIF will convert the portion you requested, but will keep the same proportions as the map picture. If this is not set, DMJ GIF will convert the portion you requested, scaling it to precisely fill the entire screen. This is useful for creating squashed or squeezed pictures, or when the original image was a bit squashed or squeezed and you want to fix it. The second option, "Trim Edges", applies only if "Same Aspect" is set. If you keep the proportions the same, there will be areas around the converted picture that are not in the selected portion of the image. If you select "Trim Edges", these areas will appear black. If this option is not set, these areas will contain more of the original image. (This may mean shifting the selected portion of the picture off-center to prevent going over the edge of the GIF.) Select "Okay" when you're done setting these options. Once Mapping is set, you can change it by clicking on the "Map" button again. You will be asked if you want to change the selected portion or if you want to disable Mapping. (Note: if you converted a picture or selected another Map picture, you will have to reload the Map picture.) If you have selected Mapping, you should NOT change the scaling factors yourself! If you do, you won't get the Page 18 picture you think you're getting. Use the "Exact" and "Guess" buttons to reset the scaling factors. Interlaced GIFs Occasionally you will find a GIF that is interlaced--that is, the picture isn't stored so that lines next to each other on the screen are next to each other in the file. This is inconvenient for DMJ GIF, since it needs to process the lines from top to bottom. So what DMJ GIF does is Uncompress the entire picture and then Scale it. Some pictures are too big to fit in memory. If this happens, DMJ GIF will write the picture, uncompressed, to the disk. This takes longer, but it's better than not being able to convert the picture at all. (This also consumes an enormous amount of disk space; let's hope that nobody creates an interlaced GIF that uncompresses to 2 Meg!) Keyboard Shortcuts DMJ GIF does have some keyboard shortcuts to buttons in the main dialog. Here they are: Help "Help" I "Info" Undo "Quit" F "From" T "To" Return "Begin" A "Add" R "Remove" S "Save" V "View" D "Dither" F1-F5 Dither "1"-"5" F7 Current Palette "ST" F8 Current Palette "STe" F9 Default Palette "ST" F10 Default Palette "STe" P "Map" G "Guess" E "Exact" Y "Type" K "Skip" ? "Prefs" M "More" All of these are in lower case. There are also some other keypresses that can be used elsewhere: Page 19 o In any "Yes"/"No" alert box, Return is "Yes" and Undo is "No". o In the "Abort Conversion" alert box, Return is "Abort", P is "Peek", and Undo is "Cancel". o In the fileselector, Return is "Okay", Undo is "Cancel", and Tab brings up the search mask dialog. o In any disk error dialog, Return is "Retry" and Undo is "Cancel". o In any situation where you have "Abort" or "Cancel", Return is "Abort" and Undo is "Cancel". Preferences This button allows you to set some of the defaults used by DMJ GIF. There are four things that you can set in this dialog: what to do about existing destination files, the default palette when loading, whether to use the ST or STe palette inside the program, and which drive to use for the temporary file. "Existing Files" allows you to set what you'd like to do about files that already exist when DMJ GIF tries to save a picture (i.e. you want to save BEARS.SPC, and there's already a BEARS.SPC on the disk). "Erase" will simply overwrite the old file, destroying it. "Rename" will rename it with the extension ".BAK", destroying any existing backup, but preserving the existing file. "Ask", the default, will have DMJ GIF ask you which option to choose every time the situation occurs. If you plan to leave DMJ GIF to work unattended, you should select "Erase" or "Rename"; otherwise, DMJ GIF will stop its work to ask you what to do about an existing file, and you won't be around... "Default Palette" refers to the "Default Palette" buttons in the main dialog. The default is "Check", which means DMJ GIF will check whichever system it is running on and use the palette for that system. You can override this feature by selecting "ST" or "STe"; this option is only acted upon when the program first loads up. (Owners of 4096 color boards for the ST can use this to set the STe palette to always be the default.) "In-program Palette" refers to which palette the program uses to display pictures. Again, the default is "Check". If DMJ GIF uses the ST palette, it will flicker STe color images to simulate the STe colors. Also, when converting Spectrum pictures to grey Map pictures, it will only use eight shades of grey. If DMJ GIF uses the STe palette, however, it will not flicker STe color images, and will use sixteen shades of grey for Map pictures. Page 20 "Temp Drive" allows you to choose the drive DMJ GIF will write temporary files to. This is only important for interlaced pictures that are too large to uncompress to RAM; DMJ GIF then writes the uncompressed picture to disk. To select the drive for this temporary file, just click on the drive letter. The default is "Run", which refers to the drive DMJ GIF was run from. If the specified drive does not exist, DMJ GIF will revert to the "Run" drive. Once you've set your Preferences, you can click on "Save" to save these preferences to DMJ_GIF3.PRF. If you save your preferences, you also save the positions of the movable dialogs (the fileselector, search mask dialog, etc.) and all of the search masks in the search mask dialog. You can click on "Use" to keep the preferences without saving them. "Cancel" aborts your choices. Bugs Wrong? How could anything possibly go wrong? Not with MY program, surely! Well, okay, perhaps just a little tiny thing went wrong. It's probably nothing major. DMJ GIF will, for the most part, tell you precisely what it is having a problem with. But if for some reason you get a dialog that tells you something like "Error xxx" then that's a bug. And when you find one, it's pretty important that you write down as much information about what you're doing, which GIF you're using, and any other programs and accessories you might have loaded at the time. Then let me know! I can't fix a bug if nobody tells me about it. I've tested DMJ GIF as best I could, on both 1 Meg and 512K machines, with a variety of AUTO folder programs, etc. but it's always possible that something can go wrong. There are some things that you can solve yourself. One very common glitch is that you'll see little specks (usually black) in your Spectrum pictures, and they'll usually form a sort of vertical line. This isn't my fault! What's happening is that the Spectrum display routines aren't properly synchronized. Usually all you have to do is reset the computer. I'd suggest actually pressing the reset button or turning the computer off; using another program to reset the computer usually doesn't cure the problem. If you still see the spots, try changing the order of the programs in your AUTO folder--one of them may be the culprit. If you have an STe, try switching to low resolution. Spectrum pictures from other programs are also susceptible to this little annoyance, but the pictures generated by DMJ GIF are much more susceptible because DMJ GIF squeezes every bit of color it can out of Spectrum mode. Fortunately this sync problem Page 21 doesn't occur too often on most machines. If you should chance to fill up the disk while trying to save a picture, DMJ GIF will tell you the disk is full, and ask that you insert a fresh disk. At this point, you should either insert a new disk and select "Retry" or decide to forget the whole thing and select "Cancel". If you select "Retry", DMJ GIF will save the picture in the root directory of the disk (NOT the folder specified in the "To" filename). I'd suggest at this point that you abort further conversions, remove all files from the batch list that have been converted, and either relocate the pictures to the root directory or save the batch list, exit the program, create the necessary folders, and reload the program and batch list and begin again. Future versions of DMJ GIF may be a bit nicer in this respect... Users of the Mega STe will obviously not be able to see Spectrum pictures while running at 16 MHz; however, once the computer is slowed down to 8 MHz the pictures display properly. It's best to leave the computer in 16 MHz mode while converting pictures, though, because conversion is a time-consuming process. I am told that using DMJ GIF 2.0, a GIF converts in about 2/5 the time as on a regular ST. I have no information on version 3.0 yet. Feedback It's extremely important that you, as a user, tell me what you want in the program! Granted, I can come up with some very clever ideas, but the best ideas come from people who know absolutely nothing about what can and can't be feasibly done, which gets programmers thinking about how it can be done. (The above is said with a smile.) Seriously, though, user feedback is critical to the improvement of any program; after all, the users are the ones who use the program. So if you have a comment, a suggestion, or if there something you don't like about the program, then PLEASE let me know! As an example of how important feedback is, let me say that letters from one of my (very enthusiastic) registered users hastened the design of the new interface by posing some very important questions. Had that person not asked the questions he did (about Mapping and STe palette) I might not have noticed several flaws in my design until it was too late. The Companion Utilities In addition to DMJ GIF, there are four companion utilities that perform a variety of useful functions. Here's a list of what they are and how to use them: SPC2PI1 Page 22 This simple program converts Spectrum pictures to DEGAS low res (.PI1) format. It's useful when you get a Spectrum picture that has 16 or fewer colors, or when you need a low res approximation of a Spectrum picture. To use this program, just select the source and destination file. The source may be in compressed (.SPC) or uncompressed (.SPU) format. The destination filename should end in .PI1, of course. You'll find that the program keeps track of two separate paths--one for the source pictures, and one for the destination pictures. You'll be warned if the source and destination files are the same, or if you try to overwrite an existing file. After selecting both the source and the destination file, the picture will load and display on the screen. Press any key to continue with the conversion, or ESC to abort. You can press ESC at ANY time to abort the conversion. The first phase of the conversion takes approximately 75 seconds, and is just a color count. When that is finished, the program will tell you how many colors were in the original picture, and the percentage of the picture that is covered by the 16 colors chosen. The higher the percentage, the more the DEGAS picture will look like the Spectrum picture. Once the picture is converted, it will be saved, and you will be asked if you want to delete the source picture. This program does recognize and use the STe palette, regardless of which computer you are actually using. If you are converting an STe Spectrum picture and plan to view it on an ST, be aware that you may get two colors that appear the same on an ST, but are actually different. In this case just load the picture into your favorite paint program and tinker with the palette until it's how you like it. After converting one picture, you can select another picture to convert, or select "Cancel" from the first file selector to exit the program. SPC2PI3 This program and SPU2SPC are the only two companion utilities that will run on a monochrome monitor. This program is like SPC2PI1, except that it converts a Spectrum picture to a DEGAS high-resolution format. This is one way to get a black-and-white version of a Spectrum picture. You use this program just like SPC2PI1, except the extension for the destination file should be .PI3. Once the picture is loaded, it will be displayed, unless you are using a monochrome monitor (obviously). Press a key to continue with the conversion. Page 23 If you have the original GIF that created the Spectrum picture, it's probably a better idea to use DMJ GIF to re-convert the original GIF, either to a 16-color image in color or a monochrome image. These programs were included to convert Spectrum pictures when you didn't have the original GIF, and do not do quite as good a job as DMJ GIF does. SPU2SPC This program does nothing but load and save the picture. It does not change the picture in any way. The idea behind the program is to provide you an easy way of converting uncompressed (.SPU) Spectrum pictures to compressed (.SPC) format, and vice versa. You use this program in the same way as SPC2PI1, except that the picture will not be displayed, and the destination file should end in either .SPC or .SPU. Sometimes you might find a Spectrum (.SPC) picture that is 50014 bytes long. These pictures are not compressed fully; you should use SPU2SPC to re-save them in .SPC format. SPC-3375 This is a slideshower/picture viewer that lets you see 3,375 of the STe's 4,096 colors on a regular ST. Just run the program, and either select a single picture (which will then be displayed) or a wildcard (like *.*) to begin a slideshow. While running a slideshow, you can use the function keys to set the speed, press the spacebar to freeze the picture, or any other key to advance to the next picture, except the ESC and UNDO keys, which abort the show. Select "Cancel" from the file selector to exit the program. SPC-3375 emulates the STe's colors by "flickering" the colors between a lighter shade and a darker shade. The eye is fooled into seeing a shade that is halfway between the two shades. Since the flickering isn't quite as fast as the monitor (it's only half as fast) you will see some visible flickering. This is reduced by using lighter and darker shades every other line, then swapping them to do the flicker. Don't stare too closely at the screen, though, because then the flicker effect is wasted. Those of you who don't have a monitor--well, the flickering is extremely bad on a television. Enough so that I wondered at a user who told me he always used the STe palette, even though he has only an ST. Then I got my monitor, and I knew why! The flickering is only half as bad on a monitor as it is on a TV. Thanks... A program this complex cannot be done without the help of Page 24 others. Thanks to all these people for their help in getting this program going. Robert and Eric Swenson, of Novato, CA, for introducing me to the ST and convincing me not to buy an Amiga. Robert Glover, of Stuart, FL, for finally getting me the Spectrum display routine, and for all of his dedicated testing. Marc Lombardo, of Ralston, NE, for being there when I felt like talking my head (and his ear) off with awesome program ideas. Bryan Woodworth, of San Jose, CA, for making all those excellent suggestions--most of which are in version 3.0--and for asking pointed questions about the new version. Tom Hayslett, of Vogelweh, Germany, for sage advice, a ride up to Düsseldorf, and a fantastic manual. All of my registered users--that check in the mail makes it all worth it.