New integrated coding schemes for computer-aided facsimile

Three coding schemes are presented that make it possible to integrate and transmit two documents on a telephone line. These schemes are designed for a computer-aided facsimile compatible with the CCITT G3 and G4 facsimile standards. Each run-length of white or black pels on a scanned line of a document is modified by one pel subject to a sequence of bits of the other document. It is possible that a document with about 3-22 kB can be embedded into the CCIT reference documents. The total amount of codes transmitted on the telephone line is about the same as that of the original facsimile document. The transmission rate may be improved by about 30% using this integration. In addition, schemes are available for protecting an embedded document from browsing