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Digital Revolution (II) - Compression Codes and Technologies

Compression and Intellectual Property

Feature Column Archive

7. Compression and Intellectual Property

From one perspective issues of compression are part of the background of engineering issues that lie behind many of the technologies we take for granted: telephone, audio CD's, fax, digital photography and television. However, once particular technologies become accepted, especially if they flourish because of industry standards for things the public feels are necessary, background issues such as compression can become the center of the important issue (for some) of making millions of dollars!

A good example of these issues was recently provided by a controversy concerning the compression standard for still images known as JPEG (Joint Photographic Experts Group). The JPEG standard for compressing still images was set in place in a way that was designed to make it possible for people who wanted to store images in a compressed format to speed the transmission of images over the Internet and to allow more room to store images in digital cameras to do so without having to pay licensing fees because patented technologies were being avoided. However, in July 2002, Forgent Networks announced claims that it owned patent 4,698,672 (Coding system for reducing redundancy) and was actively seeking to enforce the patent by seeking fees from companies that used the JPEG standard. Many claimed that this patent was either invalid or did not apply to the JPEG standard, or otherwise did not see that payments to Forgent would be necessary. However, some companies seemed convinced enough to pay Forgent to make use of the patent in their products. Forgent had acquired the patent from another company and had not done the research to develop the compression system. The dispute, interestingly, parallels the one that emerged concerning another compression image format for the web, GIFs (Graphic Interchange Format). (The PNG (Portable Network Graphics) format was in part developed to provide a patent free way to work with images on the Web.) The patent in the case of GIFs was owned by Unisys, which was the descendant of a company where Terry Welch (patent 4,558,302) had worked when the patent was given. (IBM has a patent on almost exactly the same ideas as those in Welch's patent, granted three weeks before the Unisys patent, namely patent 4,814,746. Both these patents build on the work of Jakob Ziv and Abraham Lempel, who did not seek patent protection for the earliest work they did which was published in scholarly journals.) When compression systems are used in hardware that catches on (the IBM and Welch patents have ideas that are used in the V.42bis modem compression standard in addition to the GIF format), invariably disputes arise due to the large sums of money potentially involved. Intellectual property disputes that arise in conjunction with patents, the possible future importance of which are not always understood at the time they are granted, have given rise to extended debates about the advisability of patents of certain kinds. For example, there has been much debate about so-called software patents and business practice patents, and whether or not in the long run they are good for technological innovation or hamper it. You can be sure that due to the importance of compression, these ideas will continue to be pursued, and if possible, patented.

  1. Introduction
  2. Information and compression
  3. Encoding and decoding
  4. Lossy and non-lossy compression
  5. Huffman codes
  6. Compression methods and their applications
  7. Compression and intellectual property
  8. References