HAMLAB PLUS 2.1.0 FILTER AND EXPORTER REFERENCE (c) Copyright 1990-1992 J. E. Hanway. All rights reserved. IN THIS DOCUMENT: INPUT FILTERS SUPPORTED EXPORTERS SUPPORTED ACKNOWLEDGEMENTS INPUT FILTERS SUPPORTED GIF (Graphics Interchange Format) GIF versions GIF87a and GIF89a are both supported. (GIF89 features are ignored.) Only the first image in the file is used. Non-interlaced GIF files require much less memory to convert than interlaced GIF files. NOTE: This "interlace" has nothing to do with the Amiga display. An "interlaced" GIF file stores the lines of the image in scrambled order, rather than top-to-bottom, so that, in theory, you can see the overall picture sooner while it is being displayed. Most GIF files are not interlaced. Interlaced files, when opened, will also go through an extra step during which a progress indicator will display "Buffering..." During this time their line order is unscrambled. TIFF (Tag Image File Format) Supports black&white or gray scale images with 1, 4, or 8 bit planes. Supports RGB color images with 3, 12, or 24 bit planes. Images must either be uncompressed or use PackBits compression (type 32773). SPECTRUM 512 Normal, compressed (.SPC) files supported. Uncompressed (.SPU) and .SPS files are not supported. PBMPLUS Black&white (PBM), gray scale (PGM), and color (PPM) files are all supported. Both ASCII and RAW (binary) formats are supported. MTV The RAYSHADE ray tracer by Craig E. Kolb can also write images in this format. QRT, DKBTrace Although both the QRT and DKBTrace ray tracers use the same file format, QRT uses only 21 bits of information per pixel while DKBTrace uses 24 bits. With default settings, DKBTrace pictures will look correct, while QRT pictures will be too dark, but this can be compensated by increasing the brightness. (The easiest way to do this is to load the color control settings from the "QRT_color_response" file supplied.) SUN RASTERFILES Black&white, 8-bit mapped color, and 24-bit color images are supported. Both uncompressed and run-length compressed raster files are supported. IFF ILBM (and HAM-E) Supports normal, color-mapped, interleaved bit map images with one to eight bit planes, plus HAM and HALFBRITE images. Also supports SHAM (sliced HAM), Dynamic HAM, Dynamic Hi-res, and PCHG (multi-palette) files. All versions of PCHG (12-bit and 24-bit, compressed and uncompressed) are supported. This filter will detect a HAM-E image and handle it properly. Both the HAM and REG modes of the HAM-E are supported. 18-bit and 24-bit IFF files are also supported. However, note that in this release, any CLUT (Color Look-Up Table) chunks in the file will be skipped. In order to use the information in the CLUTs, you may load them as color response curves. Targa Reads Truevision Targa file types 1, 2, 9, and 10, with 16, 24, or 32 bits per pixel. JPEG (Joint Photographic Experts Group) Supports JFIF, the JPEG File Interchange Format. JPEG files can use two kinds of compression: Huffman coding and arithmetic coding. Because supporting arithmetic coding would require licensing a patent from IBM, it is not supported. (Probably for this reason, Huffman coded JPEG images are much more common.) BMP (Windows bitmap, aka "Wallpaper" files) Reads uncompressed Windows Bitmap (.BMP) files with 1, 4, 8, or 24 bits per pixel. RLE compressed 4- and 8-bit BMP files are not supported. GL (GRASP) This filter was contributed by John Bickers. It reads .PIC and .CLP files (types C, J, L, and M) which can be extracted from MS-DOS GRASP (.GL) files using his GLSplit program. EXPORTERS SUPPORTED HamLab Temporary File Format Writes a simple, uncompressed 24-bit format. Args: none 24-bit IFF Writes 24-bit IFF files. Args: none EPS (Encapsulated PostScript) Writes a single page Encapsulated PostScript file. The file may be printed directly or imported into a publishing program that supports EPS. Can create either a gray scale or full color PostScript image. Note: your printer must support the PostScript "colorimage" operator in order to print HL+'s color postscript output. Args: BW gray scale output (default is color) JPEG Writes JFIF (Jpeg File Interchange Format) files. The amount of compression done in a JPEG file varies depending on how much loss of quality you're willing to put up with. The JPEG exporter uses a quality setting of 1-100, where 100 is the best quality (virtually lossless) and is the worst. In general, any setting above 95 is not a good idea bacause the resulting file may be large. Any setting below 10 is practically unrecognizable, and some baseline JPEG readers may not be able to read images with a quality of less than 25. The default quality setting is 75. Whenever the filter is run, it displays a requester allowing this to be changed. The requester may be suppressed by supplying the argument below when the exporter is run. (To do this, edit the HamLab.config file or run the exporter from an AREXX command.) Args: QUALITY= Sets the quality (and suppresses the requester normally used for entering the quality manually.) ACKNOWLEDGEMENTS The GL (GRASP) filter was contributed by John Bickers. PostScript is a registered trademark of Adobe Systems, Inc. The Graphics Interchange Format(c) is the Copyright property of CompuServe Incorporated. GIF(sm) is a Service Mark property of CompuServe Incorporated. Rayshade ray tracer by Craig E. Kolb. MTV ray tracer by Mark Vanderwetting. QRT ray tracer by Steve Koren. DKBTrace ray tracer by David K. Buck. PBMPLUS by Jef Poskanzer. The JPEG functionality is based on work by the Independent JPEG Group.