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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. 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