miGIF Compression - mouse and ivo's GIF-compatible compression

-run length encoding compression routines-

Copyright (c) 1998 Intuit Inc.

Permission to use, copy, modify, and distribute this software and its documentation for any purpose and without fee is hereby granted, provided that the above copyright notice appears in all copies and that both that copyright notice and this permission notice appear in supporting documentation. This software is provided "AS IS." The Hutchison Avenue Software Corporation disclaims all warranties, either express or implied, including but not limited to implied warranties of merchantability and fitness for a particular purpose, with respect to this code and accompanying documentation.

The miGIF compression routines do not, strictly speaking, generate files conforming to the GIF spec, since the image data is not LZW-compressed (this is the point: in order to avoid transgression of the Unisys patent on the LZW algorithm). However, miGIF generates data streams that any reasonably sane LZW decompressor will decompress to what we want.

miGIF compression uses run length encoding. It compresses horizontal runs of pixels of the same color. This type of compression gives good results on images with many runs; for example, images with lines, text, and solid shapes on a solid-colored background. It gives little or no compression on images with few runs, for example digital or scanned photos.

der Mouse

mouse@rodents.montreal.qc.ca

7D C8 61 5D E7 2D 39 4E F1 31 E8 B3 27 4B

ivo@hasc.com

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