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Proceedings Paper

Dual-Mode Hybrid Compressor For Facsimile Images
Author(s): Wen-Hsiung Chen; John L. Douglas; William K. Pratt; Robert H. Wallis
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Paper Abstract

A dual mode facsimile data compression technique, called Combined Symbol Matching (CSM) , is presented. The CSM technique possesses the advantages of symbol recognition and extended run-length coding methods. In operation, a symbol blocking operator isolates valid alphanumeric characters and document symbols. The first symbol encountered is placed in a library, and as each new symbol is detected, it is compared with each entry of the library. If the comparison is within a tolerance, the library identification code is transmitted along with the symbol location coordinates. Otherwise, the new symbol is placed in the library and its binary pattern is transmitted. A scoring system determines which elements of the library are to be replaced by new prototypes once the library is filled. Non-isolated symbols are left behind as a residue, and are coded by a two-dimensional run-length coding method. Simulation results are presented for CCITT standard documents. With text-predominate documents, the CSM compression ratio exceeds that obtained with the best run-length coding techniques by a factor of two or more, and is comparable for graphics-predominate documents.

Paper Details

Date Published: 28 December 1979
PDF: 7 pages
Proc. SPIE 0207, Applications of Digital Image Processing III, (28 December 1979); doi: 10.1117/12.958250
Show Author Affiliations
Wen-Hsiung Chen, Compression Labs, Inc. (United States)
John L. Douglas, Compression Labs, Inc. (United States)
William K. Pratt, Compression Labs, Inc. (United States)
Robert H. Wallis, Compression Labs, Inc. (United States)

Published in SPIE Proceedings Vol. 0207:
Applications of Digital Image Processing III
Andrew G. Tescher, Editor(s)

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