INFO: Unisys GIF and LZW Technology License Information

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Article ID: 193543 - View products that this article applies to.
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This article provides information about licensing issues regarding the .gif file format and the Lempel Ziv Welch (LZW) data compression and decompression technology. Unisys has patented this technology and requires that anyone using this technology obtain a license. This article contains links where you can get more information about the required license.


The LZW data compression and decompression technology is covered by United States Patent No. 4,558,302, Japanese Patent Numbers 2,123,602 and 2,610,084, and patents in Canada, France, Germany, Italy, and the United Kingdom.

Microsoft has obtained a license from Unisys to use the .gif file format and other LZW technologies covered by the Unisys-owned U.S. and foreign patents in a number of Microsoft products.

However, this license does not extend to third-party developers using Microsoft development products to develop applications. Third-party developers must have a license from Unisys in the form of a written agreement.

If you would like to use, sell or distribute any hardware or software using or converting the .gif file format or LZW-based technologies, you must obtain a license from Unisys.

For more information about the licenses required to use this technology, contact Unisys. For more information about hardware and software vendor contact information, visit the following Microsoft Web site: -  


Article ID: 193543 - Last Review: February 23, 2014 - Revision: 1.2
  • Microsoft Visual Studio 6.0 Enterprise Edition
  • Microsoft Visual Studio 97 Service Pack 3
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