Xref: news2.mv.net comp.os.msdos.djgpp:2129
From: elric AT wheel DOT ucdavis DOT edu (Jeffrey Taylor)
Newsgroups: comp.os.msdos.djgpp
Subject: Re: GIF routine under GRX20
Date: 22 Mar 1996 18:30:25 GMT
Organization: Davis Community Network - Davis, California, USA
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Message-ID: <4iurk1$km8@mark.ucdavis.edu>
References: <4ioesb$3sr AT rznews DOT rrze DOT uni-erlangen DOT de> <4ir6fb$a3c AT news DOT cea DOT fr> <3151CB54 DOT 24B9 AT escmail DOT orl DOT mmc DOT com>
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To: djgpp AT delorie DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp

Jim Schwarz x3-7961 (schwarz AT escmail DOT orl DOT mmc DOT com) wrote:

: <Stuff deleted>
: > 
: > You can use the 'Independant JPEG Software Group' code (freeware)
: > to read/write those formats :
: >         GIF BMP TGA PPM JPG
: <Stuff deleted>

: I would be careful where you use this code. Compuserve has been
: getting pickier and pickier about just anybody using GIF software to
: read/write GIF files.  I heard at one point that this functionality
: would be removed from the JPEG software. So if you are writting any
: commercial stuff, be careful. Note that JPEG is ok, I'm nor really
: sure of the leagal issues, if any, surrounding the other formats.

The problem is GIF uses the LZW compression algorithm which is patented.  
Unisys owns the patent and started enforcing it several years ago.  
compuServe negotiated a sort of balnket license for LZW in GIF.  They 
turned around and  asked for license fees from GIF encoder/decoder 
writers.  I suppose you could go around CompuServe to negotiate directly 
with Unisys.  There may be license problems with other parts of GIF, 
CompuServe would like some help paying the fee to Unisys.

JPEG (except for arithmetic coding which no one uses) is in the public 
domain, though fast ways to implement may be patented or trade secrets.  
IBM owns the patents on arithmetic coding, so no one implements it and no 
one pays the fees to IBM ($5K for the idea and more for their fast 
implementation).  There are other arithmetic coding forms out there that 
are not patented, but they are not the JPEG aritmetic coding.

============================================
Without my guitar, I am a poet without arms.
                        - Michael Bloomfield
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