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LZW Patent Information

License Information on GIF and Other LZW-based Technologies

Unisys U.S. LZW Patent No. 4,558,302 expired on June 20, 2003, the counterpart patents in the United Kingdom, France, Germany and Italy expired on June 18, 2004, the Japanese counterpart patents expired on June 20, 2004 and the counterpart Canadian patent expired on July 7, 2004. 


Unisys Corporation holds and has patents pending on a number of improvements on the inventions claimed in the above-expired patents.  Information on these improvement patents and terms under which they may be licensed can be obtained by contacting the following:

Unisys Corporation
Welch Patent Licensing Department

Mail Stop E8-114

Unisys Way

Blue Bell, PA  19424


Via the Internet, send email to Robert.Marley@unisys.com


Via facsimile, send inquiries to Welch Patent Licensing Department at

The above is presented for information purposes only, and is subject to change by Unisys.  Additionally, this information should not be considered as legally obligating Unisys in any way with regard to license availability, or as to the terms and conditions offered for a license, or with regard to the interpretation of any license agreements.  You should consult with your own legal counsel regarding your particular situation.