jimr@applix.com (Jim Rouleau [ext 256]) (03/28/91)
>jones@pyrite.cs.uiowa.edu writes: > (PS: Does the use of Ziv-Lempel compression for GIF images mean that >>the question of patent rights for the Ziv-Lempel algorithm applies to >>GIF images? news@ai.mit.edu responds: > >It definitely does, assuming GIF format uses LZ compression and the >patent is considered valid. Only a lawsuit will determine actual >coverage. If the algorithm differs somewhat from LZ you may be safe >(but consult a lawyer). 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 !!) jimr
victor@watson.ibm.com (Victor Miller) (04/03/91)
I hate to tell you this, but the orignal LZ2 is also patented by Unisys (originally Sperry), by Eastman et. al. Lempel and Ziv were visiting Sperry Research center at the time. In addition, there are some interferences between the Welch patent, and ours (Miller-Wegman), and our patent was filed 21 days earlier. I can only blame myself for having our paper published in a relatively obscure place (proceedings of a conference "Combinatorial Algorithms on Words" Springer-Verlag NATO ASI series) for it not being more widely known. As far as I know the LZ1 method was never patented, but, as someone pointed out Xerox has patented their variation (Greene, et. al.). -- Victor S. Miller Vnet and Bitnet: VICTOR at WATSON Internet: victor@watson.ibm.com IBM, TJ Watson Research Center
jerry@TALOS.UUCP (Jerry Gitomer) (04/04/91)
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. Ma Bell (703)683-9090 (UUCP: (until 4/15) ...uupsi!pbs!npri6!jerry