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VIEWGIF (Version 1.2) Copyright 1990 by Craig S. Buchanan SHAREWARE This program is copyrighted software. This program and its documentation may be freely copied and shared with others, as long as no charge is made, and the program and this document are unaltered. If you use this program please register by sending: $20 U.S., check or money order OR $20 Canadian, cheque or money order, OR 10 Pounds Sterling in Marks and Spencer's Gift Certificates, and any suggestions for improvements to the address listed below. Please specify the version number you are using (1.1). Your support will ensure that improvements are made. 4-319 Mackay St. Ottawa, Ont. K1M 2B7 First, a thank you. This is a thank you to all of those users of VIEWGIF who have registered. Your support makes improvements like this release possible. Your feedback on VIEWGIF is invaluable. Without support VIEWGIF would still be at version 0.6. Note that if you are registered for a previous version of VIEWGIF you do not need to reregister for version 1.2. Table of Contents: 1. WHAT'S NEW? 1 2. INTRODUCTION 1 3. FUNCTION OVERVIEW 2 3.1 FILE - menu 2 3.2 EDIT - menu 3 3.3 MODE - menu 5 3.4 Mouse Shapes 7 4. HOW TO USE VIEWGIF 7 4.1 Guide to File Types 7 4.2 The COLOUR mode 9 4.3 The GRAY mode 9 4.4 The FL and CP8 formats 10 4.4 Use with SPECTRE 128/GCR 10 4.5 Overscan 11 5. KNOWN SHORTCOMINGS/BUGS 12 6. ENHANCEMENTS UNDER CONSIDERATION 12 7. PROGRAM HISTORY 13 8. REGISTRATION FORM 17 1. WHAT'S NEW? 1. A Full Screen mode has been added. The entire ST screen can now be used to display images. By simply pressing the escape key the image in the top window will replace the entire screen. This feature only works in Native ST resolutions. (ie. Full Screen Mode does not work with Overscan or large screen monitors.) 2. Degas and Neochrome save uses Full Screen Mode to preview. The image being saved can be adjusted using the Full Screen Mode controls. Selecting the final clipping of a large image is now much easier. The save is unchanged when using non native ST video modes. 3. Much improved IFF file loading. Version 1.1 had trouble understanding many IFF files. Version 1.2 can read many more IFF files. 4. An Added Bonus. NeoDesk 3.0 Icons. The included .NIC file contains icons for use with NeoDesk 3.0. Icons are provided for most of the filetypes VIEWGIF uses. Note that the NeoDesk 3.0 documentation claims that 3.0 icons cannot be used with earlier versions of NeoDesk. 2. INTRODUCTION So what are GIF files and why should I be interested? GIF files are computer graphic images stored in a compressed, hardware independent manner. The hardware independent format makes it a standard for moving images between different computers. VIEWGIF allows your ST to show graphics created on a PC, an Amiga, or whatever, even if the original image has more colours or pixels than the ST can display. It also allows you to convert your Atari ST images into GIF format for exchange with other systems. VIEWGIF is GEM based and operates in all three resolutions. Images are displayed in scrollable windows. Once an image is loaded it can be saved in NEO, Degas , Macpaint (in Monochrome) or FL Format. The image can also be cropped and shrunk to fit the ST screen. VIEWGIF also allows a GIF image to be directly transformed into AIM (the Atari Image Manager) and Spectrum 512 pictures. This allows the 512 colour Spectrum mode to be used to display 256 colour VGA images. 1 3. FUNCTION OVERVIEW Most menu items have keyboard equivalents which are noted at the end of each menu item. A caret (^) denotes a control key while a small triangle denotes an alternate key. The equivalents are listed with their corresponding functions in the list below. 3.1 FILE - menu GIF INFO: (ALT I) Given a GIF file it displays the image attributes including dimension, number of colours, size of colour palette, etc. It also tries to determine the image's original video format. LOAD FILE... (ALT L) Displays the file load form. Allows the following file types to be loaded: GIF (ALT G), IFF (ALT A), LBM (ALT B), MAC (ALT M), NEO (ALT N), DEGAS (ALT D), FL (ALT F), CP8 (ALT P). The keyboard equivalents can be used to bypass the file type selection form. The GIF, IFF and LBM modes read in the file and then translate it to the current ST format according to the options set in the MODE menu. The two modes are COLOUR and GRAY. (See discussion of MODE.) The DEGAS mode currently reads uncompressed (PI#) DEGAS only. The MAC mode will read and translate into the current resolution any MacPaint or Mac StartUpScreen image. Determination of image type is automatic. The CP8 mode always uses the dispersed dot dither to translate the image into the current ST format regardless of the MODE options COLOUR and GRAY. (See CP8 discussion in TRANSFORM.) The dispersed dot dither MODE options HISTO and SCALED are used. (See MODE discussion.) If the file contains more than one channel (image) the user will be prompted for the channel to load. The channel number appears after the filename in the window border enclosed in square parenthesis. Each image is displayed in its own window and each window has its own colour palette. The top window's colour palette is always used. The original image dimensions are maintained but the CLIP and SHRINK functions can be used to reduce the image size. The title bar of each window contains the image filename and the information bar contains a description of the image colours along with the dimensions of the image. If the image is in colour then the information bar contains [a:b] where 'a' is the number of colours in the original image and 'b' is the number of Atari ST colours. If the image is displayed in gray scale then the information bar contains [a:b] where 'a' is the number of colours in the original image and 'b' is the number of grays in the 2 image. SAVE FILE... (ALT S): Displays the file save form. Allows the following file types to be saved: GIF (CTRL G), FL (CTRL F), NEO (CTRL N), DEGAS (CTRL D), MacPaint, (CTRL M), Mac StartupScreen (CTRL T). The current image (top window) is saved in the selected file type. The keyboard equivalents can be used to bypass the file type selection form. The DEGAS mode writes only uncompressed (PI#) DEGAS. If a native ST video mode is being used the FULL SCREEN MODE is used to preview and adjust the clipping of the image to be saved. (See Section 3.3 - FULL SCREEN MODE). After adjusting the clipping (if necessary) using the arrow keys press RETURN to save the image or ESCAPE to cancel the save. When overscan or another non native ST video mode is used this full screen view is not displayed. A window clipping function is provided. (It is presumed that in these cases a full NEO or DEGAS picture will fit inside a window making the preview unnecessary.) Save FL saves the entire image viewed in the current window regardless of dimensions. The confirmation dialog allows an optional compression routine to be used in saving the image. The use of the compression routine adds only a small overhead to FL loading. The compression routine used is a simple form of Run Length Encoding so only images with large single colour areas will compress significantly. Dithered images will usually not compress significantly. CLOSE: (ALT C) Closes the Top Window. QUIT: (ALT Q or CTRL C) Exits the program. 3.2 EDIT - Menu. CLIP: Crops the current image at one of the four window boundaries. Simply size and scroll the window to the correct place, select CLIP, and then select the clipping corner. 3 SHRINK: (ALT K) Halves the image size using one of three methods. LINEAR works best on 256 colour images while the two STAGGERED modes work best on 4 and 16 colour images where dithering/patterning has been used to simulate more colours. Many EGA (an IBM graphic mode) images use a checkerboard pattern to simulate more than 16 colours. A linear shrink of the image will produce only one colour in the checkerboard, the staggered modes are designed to preserve the colour dither. COLOURS: Allows the Colour Palette of the Top Window to be edited. The modified colours can be SAVED (stored with the window), USED (not stored with the image but remain as the current colours), and CANCELLED. DESKTOP: (Undo) Returns the colour palette to your desktop colours. To return to an image's palette use COLOURS or make another picture the active (top) window. TRANSFORM ...: Allows a GIF image to be converted to either AIM, CP8[1], CP8[3] or SPU (Spectrum uncompressed) without first being converted to screen format. This allows the maximum of image data to be maintained. Colour conversion is used to produce SPU and CP8[3] images, gray scale conversion is used to produce the AIM and CP8[1] images. When converting an image to SPU that is larger than 320x199 the top left hand corner of the image will be used. When converting to an AIM image both an .IM and a .HD file are produced. When converting an image to CP8[1] a false gray routine will be used if the image contains less than 256 colours. The false gray routine tries to ensure that two colours with the same gray value are encoded with slightly different gray values. The false gray routine is used to prevent 16 colour images from becoming 4 gray level images. The translation to CP8[3] images is intended for 256 colour GIF images but any GIF image will work. By default a CP8[3] image is interpreted as containing the red image in channel 1, the green image in channel 2, and the blue image in channel 3. The multi channel CP8 format allows up to 16 channels to be encoded. NOTICE: GIF to CP8[3] conversion currently requires a great deal of memory and may result in a file three times as large as the original. Why translate to CP8? The CP8 format is designed for 8 bit gray scale images, 24 bit colour images and multi spectral images. It is a hardware independent, compressed format like GIF but unlike GIF it can 4 be compressed in very little time and decompressed almost instantly. The CP8 format trades a decrease in compression performance for a large increase in decompression speed. The CP8 format also allows the decompression routine to detect corrupted data while the GIF format does not. (This is a small point as the picture will show any file corruption dramatically.) 3.3 MODE - Menu. COLOUR: When COLOUR is selected LOAD GIF, IFF and LBM translates the file into a colour picture. This mode is obviously unavailable in monochrome mode. GRAY: When GRAY is selected LOAD GIF, IFF and LBM translates the file into a gray scale picture. This mode is preselected in monochrome mode. COLOUR OPTIONS...: Displays the colour option form. The following selections are available: FREQUENCY, COLOUR SPACE, IGNORE NB. FREQUENCY: When selected colours are chosen based on their frequency in the image. This is the routine used in older versions of VIEWGIF. COLOUR SPACE: When selected colours are chosen based on their frequency and distribution in colour space. IGNORE NB: Many monitors cannot display the darkest colours in the ATARI colour palette. Selecting IGNORE NB prevents the darkest colours from being used. This option is only used if COLOUR SPACE is selected. GRAY OPTIONS...: Displays the gray option form. The following selections are available: ORDERED, DISPERSED, HISTOGRAM, SCALED, ENHANCE. ORDERED: Only available in monochrome mode. When selected an ordered dither is used to convert the gray scale image into monochrome. (This routine may be phased out in subsequent versions of VIEWGIF.) 5 DISPERSED: When selected a dispersed dot dither is used to convert the gray scale image to 2, 4, or 8 shades of gray depending on the current resolution. Takes longer than ORDERED but produces much better results. HISTOGRAM: When HISTOGRAM is selected all DISPERSED gray dithers use histogram equalization to maximize the contrast of the resultant picture. The HISTOGRAM alternative is SCALED. HISTOGRAM distorts the gray scale linearity resulting in an artificial image. SCALED: When SCALED is selected all DISPERSED gray dithers use scaling to insure full gray scale coverage in the resultant picture. The SCALED alternative is HISTOGRAM. SCALE preserves the gray scale linearity resulting in a truer image than HISTO. Use SCALED if a HISTOGRAM image appears "washed-out". ENHANCE: When ENHANCE is selected an edge enhancement is applied to the image before it is dithered. Use ENHANCE if the dithered image appears blurry. The HISTO option should always be used with ENHANCE to ensure good results. FULL SCREEN MODE: The image in the top window replaces the entire screen. A set of keypresses are then used instead of the GEM interface. The keypresses are summarized in an instruction list which appears when the full screen mode is entered. The supported keypresses of the entire screen mode are: Arrows: Scroll Left, Right, Up or Down. Shift Left Arrow: Left Side. Shift Right Arrow: Right Side. Shift Up Arrow: Top. Shift Down Arrow: Bottom. Esc: Back to GEM! The full screen mode is only available when the ST is using a native video mode. It is not available when using OVERSCAN or a large screen monitor. 6 3.4 MOUSE SHAPES A variety of mouse shapes are used to keep the user informed about system progress. The mouse shapes translate as follows: Diskette: Reading or writing from disk, Magnifying Glass: Examining image, Bench Vise: Compressing or decompressing image, Paint Brush: Painting Screen Image, Star: Edge Enhancement. The shapes correspond roughly to the programs current action. A large exception is the GIF, IFF and LBM reads and writes which read/write, decompress/compress, and sometimes paint all at the same time and is represented only by the Diskette mouse shape. 4. HOW TO USE VIEWGIF This section is intended to help you get the most from VIEWGIF. 4.1 Guide to File Types The following file types are used by VIEWGIF: GIF: 'Graphic Interchange Format'. A machine independent compressed graphic format. Designed for Compuserve. Max Colour Planes: 8 Bits (256 Colours) Max Palette Size: 24 Bits (16777216 Colour choices) Max size: 65536 x 65536. May contain several images. Typically: 320x200 or 640x480 in 16 or 256 colours. IFF: 'Image File Format?'. Used on the Commodore Amiga. Max Colour Planes: 8 Bits (256 Colours) Max Palette Size: 24 Bits (16777216 Colour choices) Max size: 65536 x 65536. Typically: 320 x 200 in 32 colours. LBM: 'InterLaced BitMap?'. Used by Deluxe Paint on the PC and Amiga. Max Colour Planes: 8 Bits (256 Colours) Max Palette Size: 24 Bits (16777216 Colour choices) Max size: 65536 x 65536. Typically: 320x200 or 640x480 in 16 or 256 colours. 7 MAC: 'MACintosh file'. Contains either a Macpaint picture (MPNT) or a Macintosh StartupScreen (SCRN). MPNT: 'MacPaiNT'. A compressed monochrome format used on the Macintosh. Planes: 1 Bit (Monochrome) Size: 576 x 720 SCRN: 'startupSCReeN' An uncompressed Macintosh screen image. Planes: 1 Bit (Monochrome) Size: 512 x 342 FL: 'Fast Load' An Atari format for arbitrary sized raster images. Planes: 1, 2, or 4. (Monochrome, 4 Colour, 16 Colour) Max Palette Size: 12 Bits (4096 Colours) Max Size: 65536 x 65536. CP8: 'ComPressed 8 bit image' A hardware independent format for arbitrary sized gray scale images (CP8[1]), 24 bit colour images (CP8[3]) and multispectral images (CP8[n]). Max Planes: 8 bit (256 gray levels) Max channels (images): 16 Max Size: 65536 x 65536. NEO: 'NEOchrome' Contains an Atari low-resolution, 16 colour screen. Used by NEOchrome and countless other Atari paint programs. Colour Planes: 4 (16 Colour) Colour Palette: 9 Bits (512 Colours) Size: 320 x 200. PI?: 'degas PIcture' Contains an Atari screen in high, medium or low resolution. Used by Degas, Degas Elite and countless other paint programs. Colour Planes: 1, 2, or 4. (Monochrome, 4 Colour, or 16 Colour) Colour Palette: 9 Bits (512 Colours) Size: 640 x 400, 640 x 200, 320 x 200. SPU: 'SPectrUm picture' Contains a Spectrum 512 uncompressed image. Spectrum 512 allows the Atari ST to display 512 colours on screen at once. Colour Planes: 4 (16 Colours per Palette) Colour Palette: 9 Bits (512 Colours) Number of Palettes: 597 (3 Palettes per line) Size: 320 x 199 8 IM and HD: 'Atari Image Manager and HeaDer files' Contains a gray scale image in a hardware independent format. The 'Atari Image Manager' allows the ST to be used for image processing. Highly recommended. The colour AIM format is not supported. Planes: 8 (256 gray levels) Max Size: 65536 x 65536 Typically 512 x 512 in 256 Gray Levels. 4.2 The COLOUR Mode When loading an image in colour mode two situations can occur: 1. the image can be displayed at the current resolution and 2. the image contains more colours than can be displayed at the current resolution. In case 1 the image is simply loaded and displayed. In case 2 VIEWGIF must choose colours with which to represent the image. VIEWGIF has two colour choosing routines; FREQUENCY and COLOUR SPACE. If the image is unsatisfactory with one routine try the other routine. A special mode of COLOUR SPACE is IGNORE NB. Select IGNORE NB if your monitor cannot display the darkest colours in the Atari Colour Palette. If IGNORE NB is selected the COLOUR SPACE will not allocate valuable colour palette entries to colours your monitor cannot display. You can tell an image has undergone colour choosing when the number of colours in the information line are not equal. (ie. [256,47] which stands for 256 original colours, 47 Atari ST colours.) If an image has more colours than can be displayed try the 'GRAY' mode. 4.3 The GRAY mode. When the GRAY mode is selected GIF, IFF and LBM images are converted to gray scale images and then dithered. The gray mode is intended to be used when the image cannot be accurately represented at the current ST resolution. The gray scale dither allows much more image detail to be preserved than when using the COLOUR mode. Monochrome users have a choice of two dithering routines: ORDERED and DISPERSED. The ORDERED dither uses fixed patterns to produce the artificial gray levels. It is fast but produces relatively low quality images. The DISPERSED dither uses error propagation to produce the artificial gray levels. It takes much longer but produces much better images. The dithering routine should normally be left on DISPERSED. The distribution of gray levels is adjusted to prevent images from being too dark or too light. (ie. all black or all white). VIEWGIF supports two methods for distributing the Gray Levels: HISTOGRAM and SCALED. The SCALED method distributes the gray levels evenly between black and 9 white ensuring full coverage of the artificial grays. The HISTOGRAM method distributes the gray levels according to their image frequency ensuring maximum contrast in the image. The HISTOGRAM method should always be tried first. If the resulting image appears 'washed out' then the SCALED method should be tried. (Images with large coloured borders often appear 'washed out'.) VIEWGIF also allows edge enhancement to be performed on the image prior to dithering. A natural result of dithering is a loss in image sharpness, this loss can be alleviated by first enhancing the image. If the resulting image is blurry try ENHANCE. The ENHANCE mode should normally be off as a by product of edge enhancement is increased image noise. The distribution method HISTOGRAM should always be used with ENHANCE to ensure adequate gray coverage. 4.4 The FL and CP8 formats Loading and translating large GIF images can take a long time. The resulting picture often cannot be saved in NEO or DEGAS format without losing much of the picture. The FL format was added to allow arbitrary sized Atari format images to be loaded and saved quickly. The CP8 format allows the gray scale equivalent of a GIF image to be loaded quickly. The FL format is perfect for large screen or overscan demos. Simply load the GIF image once and save it as FL. The down side of these images is that they can be quite large. The CP8 format is hardware independent and allows VIEWGIF to load a CP8 file at any resolution just like a GIF file. Unlike a GIF file a CP8 file contains a gray scale image. Use the TRANSFORM... option GIF => CP8[1] to convert a GIF image to a CP8 image. Once converted the image can be loaded and dithered much more quickly than the original GIF image. 4.5 Use with SPECTRE 128/GCR Now that VIEWGIF reads and writes MacPaint images it is a natural for moving monochrome pictures between your ST and your MAC. Degas images can be saved as MacPaint and then loaded with any Macintosh paint program. Likewise Macintosh Clip Art can be loaded and saved as Degas for use with any Atari paint program. The MAC files produced by VIEWGIF are true MacBinaries. When moved to a Macintosh using TRANSVERTER or a Terminal Program they will be recognized and stored as true Macintosh files. (TRANSVERTER is the TRNSV452.PRG program that comes bundled with SPECTRE.) TRANSVERTing a file requires an MFS diskette or hard drive partition. 10 To move your .MAC file to a Spectre/MAC disk with TRANSVERTER. 1. Run TRANSVER.PRG 2. Use 'Assign Drives' to point to source and destination drives. 3. Select 'ST->MAC' 4. Select the .MAC file (TRANSVERTER will not ask for the Macintosh file type, it's in the Macbinary.) 5. Answer 'Spectre or Mac' format if required. To move your MacPaint file to the ST with TRANSVERTER. 1. Run TRANSVER.PRG 2. Use 'Assign Drives to point to source and destination drives. 3. Select 'MAC->ST' 4. Select the Macpaint or StartupScreen file 5. Answer 'Spectre or Mac' format if required. 4.6 OVERSCAN VIEWGIF works with native STs as well as large screen monitors. In the documentation for VIEWGIF 0.8 I noted that OVERSCAN could be used to increase screen resolution. Several registered users asked what OVERSCAN was so here is an explanation. OVERSCAN is a technique whereby the screen borders can be used for ordinary screen display. This allows many more lines and rows to be displayed on your existing monitor. To further increase the displayed resolution the vertical and horizontal size or your monitor can be adjusted. The largest increase in resolution comes when a multi-sync monitor is used with the ST. The resolution is set with a simple program called OVERSCAN.PRG in the AUTO FOLDER. My Atari Monitors display the following resolutions with OVERSCAN: Low Resolution: (320 x 200) Now 400 x 280 High Resolution: (640 x 400) Now 672 x 480 The increased resolution is compatible with the GEM desktop and any properly written GEM applications. OVERSCAN requires TOS version 1.2 (MegaTOS) or version 1.4 and a simple hardware patch. On a mega ST the patch is simply a switch disabling/enabling a video line. The switch allows OVERSCAN to be disabled/enabled at boot up. Older STs require an additional transistor. Total cost in parts is less than $10. The complete procedure along with digitized images of the trace cuts to be made (for several board versions) is contained in the file OVERSCAN.ARC which is available on many BBSes. If you are thinking of installing OVERSCAN please have a competent technician do the work. It involves cutting a pair of traces on the ST motherboard. I had a local Atari store service technician install mine. 11 The modification will void your warranty if you still have one. I take no responsibility for OVERSCAN or its use. I have no connection with the developers of OVERSCAN. 5. KNOWN SHORTCOMINGS/BUGS A. Window colours can still go to black on black on some images. This is best fixed by remembering the DESKTOP colour menu key equivalent (UNDO). B. GIF decryption is slow, even in 'C'. Decrypting a GIF image is a painful, bit-twiddling, CPU intensive process. The speed of this code could be increased by using hand optimized assembler routines. Such routines could be developed if user support warrants it. Alternatively a "Fast VIEWGIF" may be offered to registered users. 6. ENHANCEMENTS UNDER CONSIDERATION A. Support 4096 Colour Mode of STE, TT and Modified ST. I am very interested in supporting the STEs colour palette but no one has requested it! B. Load any NEO or Degas picture in any resolution. C. Add more support for AIM. (Atari Image Manager). Add load AIM. D. Add any of the following GIF and non-GIF "TRANSLATE..." options: translate IFF to GIF, translate LBM to GIF, translate CP8 to AIM, translate AIM to CP8, translate GIF to Colour AIM, translate CP8 to GIF. (Alternatively the program 'GRAY.PRG' which already includes many of these features along with full gray-scale editing capability could be released as SHAREWARE. (Before VIEWGIF gets too big.)) E. Add load/save and translate support for TIFF images. F. Add load/save and translate support for IMG images. G. Load entire GIF images before decompressing them. This would speed up the GIF load but it would also require as much as twice the memory to work. H. Add additional support for 24-bit colour CP8 images. This would be in the form of two translate option: Translate 3 CP8 images into a 24-bit CP8 image. Translate a 24 bit CP8[3] to GIF. I. Add elementary paint functions. This would turn VIEWGIF into a virtual screen paint program. (I think VIEWGIF is big enough already but I think a separate virtual paint program has merit.) J. Make the SHRINK size variable. Allow the user to enter an arbitrary shrink ratio. ie. Shrink by 1/5, 2/3 etc. (Already available in 'GRAY.PRG'.) 12 K. Add Compressed Degas format load/save. L. Add Memory Lean GIF read option. The Lean option would trade reduced memory requirements for a reduction in image quality. L. Add TT video mode support. (640x480x16, 1280x960x2, 320x400x256) I saw the TT for the first time yesterday (Oct. 31, 1990). I am very interested in supporting the 256 colour mode but will wait until it is requested. M. Add an AVERAGE option to the SHRINK routines. An average routine would allow gray dithered images to be shrunk. It would return an error message when given a colour image. N. Supply a separate GIFCLIP program with VIEWGIF. GIFCLIP would allow a GIF image to be clipped or cropped and possibly scaled and then saved without a loss in colour resolution. If you want to see any of these enhancements (or any of your own) simply register and make a request. What would you find useful? Many of the features added with each release came from requests. 7. PROGRAM HISTORY 0.6 First SHAREWARE release of VIEWGIF. 0.7 Fixed bugs due to differences between TOS 1.2 and TOS 1.1 [(c) 1985]. Low Res now works under TOS 1.1 [(c) 1985]. Neo/Degas save now works under TOS 1.1 [(c) 1985]. NOTE: VIEWGIF 0.6 worked under TOS 1.1 [(c) 1985] if key commands were used instead of menu items. WHAT'S NEW? - Changes in VIEWGIF 0.7. 1. Low Res now works under TOS 1.1. [(c) 1985]. 2. Neo/Degas save now works under TOS 1.1 [(c) 1985]. 3. Slight rearrangement of menu items. 4. Control, Alternate abbreviations changed in menu items. 0.8 Released February 25, 1990. 1. All "translate..." conversions now work. This includes CP8, AIM, and SPU. 256 colour GIF images can now be converted to 256 gray scale AIM images for image processing using the "Atari Image Manager". These gray scale images can also be stored and viewed using the compressed CP8 format. 2. Load CP8 option added. 3. Improved monochrome support. A dispersed dot dither mode has been added. While the dispersed dot dither is much slower than the ordered dither the results are much better. The dispersed dot dither has two modes, scaled and histogram equalization. 4. Now supports OVERSCAN fully. The OVERSCAN modification allows an ordinary Atari ST to display an increased resolution screen in all three ST modes. When activated OVERSCAN allows an entire Degas picture to be displayed 13 INSIDE A WINDOW. VIEWGIF looks great with OVERSCAN displaying full 320x200, 640x200 and 640x400 images inside GEM windows. Overscan requires a very simple and inexpensive modification to your ST. 5. LOW and MED resolution option to display GIF colour images as GRAY scale images. Displaying a 256 colour GIF image on the ST's 16 or 4 colour display involves a lot of compromise in the image quality. Converting the image to a gray scale image and using an intelligent dithering routine often results in much more image detail being preserved. This can be most clearly seen in Medium Resolution where the gray scale images are clearly superior to the colour images. 0.9 Released April 3, 1990. 1. Support for multi-channel CP8 images added. Multi channel CP8 allows 24-bit colour images as well as multi spectral images (such as LANDSAT) to be encoded. The support is in the form of an improved LOAD-CP8 facility and a new translate option: GIF to CP8[3]. 2. Dispersed dot dither is now nearly twice as fast. The dispersed dot dither is compute intensive. It has been rewritten for vastly increased speed. 3. Histogram Equalization has been repaired and improved. Previous routine would occasionally display white regions as black. 4. Load CP8 bug fixed. CP8 files larger than 64K did not load properly. (A user alerted me to this bug only a few days after the release of version 0.8.) 5. Minor changes and improvements. (In response to suggestions made by registered users.) Image windows are opened full size. Almost all "ACTION CANCELLED" dialogs have been removed. The full size window button now works properly. More mouse shapes have been added. 1.0 Released June 10, 1990. 1. GIF read now nearly twice as fast as in previous versions. The GIF read routine has been optimized for speed and is also more robust than in previous versions. The GIF write is also faster. 2. "Fast Load" raster file format added. Arbitrary size raster images can now be saved/loaded directly. This file format allows a large GIF image to be converted once and then saved in a form which loads very fast. Perfect for large screen demos. The "FL" format includes a very fast, optional compression routine to save disk space. 3. GIF binary read/write repaired. 14 The binary (monochrome) GIF read/write used in previous versions of VIEWGIF did not conform to the GIF standard. (Only VIEWGIF could read a binary GIF file created with VIEWGIF.) Binary GIF files now load and save properly. 4. Scaled Equalization has been repaired. Previous routine would occasionally display white regions as black. 5. Minor changes and improvements. The file menu has been modified. 'Load Degas' has been replaced by 'Load PI#', where # = 1, 2 or 3. GIF save confirmation dialog now contains window number. GIF information now displays interlace flag. 1.1 Released August 25, 1990. 1. New file formats .IFF and .LBM added. VIEWGIF is not just for GIF anymore! IFF and LBM files can be viewed in colour or grayscale just like GIF files. 2. Support for SPECTRE 128/GCR users, can now WRITE MacPaint. Monochrome users can now save in MacPaint or Mac StartupScreen. These files are in "MacBinary" format, simply run through TRANSVERTER to move to a Spectre or MAC disk. 3. Mac StartupScreens can now be loaded. VIEWGIF automatically determines if a .MAC file is a MacPaint picture or a Mac StartupScreen and loads the file in any resolution. (Would anyone like to see this feature when loading NEO and Degas pictures?) 4. Gray Scale Edge Enhancement option added. If the dithered image is blurry select the enhancement option and reload. 5. New colour selection routine added. A new colour option menu allows the user to choose between the previous colour selection routine and a new 'colour space' routine. This routine is still being refined. An additional option of the 'colour space' routine is the 'ignore near black' option. If your monitor (like many) cannot display the darkest colours of the Atari palette selecting 'ignore near black' will prevent them from being used. 6. New file load and file save forms added. The file menu list had become too long. Two new forms are in place for selecting the load and save file types. 7. Gray Scale and Colour options are now in forms. The forms are intended to be more self explanatory than the previous menu entries. 15 1.2 Released October 31, 1990. (Happy Halloween!) GIF is a trademark (tm) of Compuserve Inc, an H&R Block Company. 16 8. REGISTRATION FORM Remit to: Craig S. Buchanan 4-319 Mackay St. Ottawa, Ont. Canada K1M 2B7 ---------------------------------------------------------------------- Payment: $20 U.S., check or money order __ $20 Canadian, cheque or money order __ 10 Pounds Sterling in Marks and Spencer's Gift Certificates __ ---------------------------------------------------------------------- Version: 1.2 Name: ________________________________________ Company: ________________________________________ Address: ________________________________________ ________________________________________ ________________________________________ ---------------------------------------------------------------------- Comments / Suggestions: __________________________________________________ __________________________________________________ __________________________________________________ __________________________________________________ __________________________________________________ __________________________________________________ __________________________________________________ 17