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Thread: GIF, LZW Patent Issues
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face BY : Mike Hardwick email (remove spam text)



Dan,

That's similar to the solution we adopted... The source images have low
complexity. We translate GIFs supplied by the customer to BMP format, using
the 8-bit RLE option, with a standard translation tool. Then we extend the
BMP files to include a field for the color specified as transparent in the
original GIF files. The resulting morphodite image format is used
exclusively in our system. It's working okay now, but I still wish we
didn't have to use this odd-ball file format...

Mike Hardwick
Decade Engineering


>Try looking at the PCX format. It uses a form of RLE compression and has
fairly
>good results on non-photgraphic images. By that I mean images with large
areas
>of solid colors compress very well. Images with lots of "noise", such as
photographic
>images tend not to compress as well. In the past I used PCX images and
designated
>one of the color values as trasparent in my drawing routines.
>
>The code for PCX decoding can be very small and uses very little ram.
Likewise
>it can also be very fast.
>
>Good Luck!
>
>Oh, yah,,,, try looking for information on the LZ compression algorythm.
It is the
>pre-cursor to LZW and is not protected, AFAIK. The W is the initial of the
person
>whom modified LZ into LZW and his company patented it. I think the W stand
for
>Welch. The L and Z are some strange names that I cannot spell, but
phonetically
>they sound like "Lem-ph" and "Zip-fell" or something to that effect. Sorry
it was over
>10 years ago that I worked with this stuff.

Mike Hardwick, for Decade Engineering
Tel: 503-743-3194 ~ Fax: 503-743-2095
Post: 5504 ValView Dr. SE, Turner, OR 97392 (USA)
Email: KILLspammikespamBeGonespamRemoveMEdecadenet.com ~ Web: http://www.decadenet.com

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