Abstract of U.S. Patent No. 5,398,066 (March-14-1995)
Method and Apparatus for Compression and Decompression
of Digital Color Images
Inventors: Eugenio Martinez-Uriegas, Hewitt D. Crane, and John D. Peters
Assignee: SRI International, Menlo Park, California.
Color image compression and decompression is achieved by either spatially and chromatically multiplexing three digitized color planes, such as RGB (Red-Green-Blue), into a digital array representative of a single digitized spatially- and chromatically-multiplexed plane, or, by use of a color imaging device, capturing an image directly into a single spatially-multiplexed image plane, for further compression, transmission and/or storage. At the point of decompression, a demultiplexer separately extracts, from the stored or transmitted image, data to restore each of the color planes. Specific demultiplexing techniques involve correlating information from other planes with the color plane to be demultiplexed. Various techniques of entropy reduction, smoothing and speckle reduction may be used together with standard digital color compression techniques, such as JPEG. Using lossless JPEG about 6:1 data compression is achieved with no losses in subsequent processing after initial compression. Using lossy JPEG substantially higher data compression is achievable, but with proportional loss in perceived image quality.
33 Claims, 20 Drawing Sheets
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