Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!uupsi!pbs.org!TALOS!jerry
Newsgroups: comp.compression
Subject: Re: LZW Patent rights (was looking for info on image compression)
Message-ID: <1738@TALOS.UUCP>
From: jerry@TALOS.UUCP (Jerry Gitomer)
Date: 3 Apr 91 21:38:44 GMT
References: <1173@applix.com> <2741@sirius.ucs.adelaide.edu.au>
Distribution: world
Organization: NPRI, Alexandria VA
Keywords: greedy large companies
Lines: 37

simon@ITD.Adelaide.EDU.AU (Simon Hackett) writes:

|In article <1173@applix.com>, jimr@applix.com (Jim Rouleau [ext 256]) writes:
||>   Now I'm confused.  According to the TIFF 5.0 spec (prepared jointly
||> by Microsoft and Aldus) compression scheme 5 is "LZW Compression".
||> In fact, "A Technique for High Performance Data Compression" by
||> Terry A. Welch is cited as the reference, which is then fully
||> described in the spec.
||>
||>   Are Microsoft and Aldus at risk for doing this ???  (maybe my
||> TIFF reader should not support scheme 5 !!)
||>

|        They're arguably at some risk if the parent issue winds up being
|legally tested. If I have my facts straight, the algorithm which xerox are
|trying to assert patent rights over is _precisely_ LZW as described by
|Welch (Who is the "W" in LZW), as described in exactly the paper you cite.

|        The reason is apparently because Welch was working for Xerox when he
|wrote that paper, and so they're asserting ownership over his invention.

	Terry was working for Sperry when he wrote the paper.  So, if Xerox
	is trying to assert patent rights they must be using a basis other
	than employment.

|        Look for a the public release of a new variation on LZ by Ross Williams
|(ross@spam.ua.oz.au), appearing Real Soon Now, and generated from LZ, rather
|than LZW, so it's theoretically free of this patent "problem".

	Hopefully he won't call it LZW(illimans) to avoid confusion :-)

			Jerry

-- 
Jerry Gitomer at National Political Resources Inc, Alexandria, VA USA
I am apolitical, have no resources, and speak only for myself.
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