Dual-Mode Hybrid Compressor For Facsimile Images

Wen-Hsiung Chen; John L. Douglas; William K. Pratt; Robert H. Wallis

doi:10.1117/12.958250

28 December 1979 Dual-Mode Hybrid Compressor For Facsimile Images

Wen-Hsiung Chen, John L. Douglas, William K. Pratt, Robert H. Wallis

Proceedings Volume 0207, Applications of Digital Image Processing III; (1979) https://doi.org/10.1117/12.958250
Event: 23rd Annual Technical Symposium, 1979, San Diego, United States

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.

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Wen-Hsiung Chen, John L. Douglas, William K. Pratt, and Robert H. Wallis "Dual-Mode Hybrid Compressor For Facsimile Images", Proc. SPIE 0207, Applications of Digital Image Processing III, (28 December 1979); https://doi.org/10.1117/12.958250

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