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Open Access Publications from the University of California

Progressive Color Block Coding of Bilevel Scanned Documents


The efficient coding of scanned documents is a problem of growing importance. The international facsimile transmission standards of 200 dpi, as well as 300 dpi high quality document scanning for computer use, are of interest. We present, and discuss, a progressive coding technique, building upon color shrinking, i.e., the gross, data dependent localization of the black portions of an image, that we have presented previously. We propose two intermediate quality standards, 100 dpi binary, and 100 dpi grey scale, which provide high compression, as well as a readable version of documents, specially suited for a computer workstation display.

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