Nippon Telegraph and Telephone Public Corporation

Kokusai Denshin Denwa Kabushiki Kaisha

Toyomichi Yamada

Yasuhiro Yamazaki

Yasushi Wakahara

Kiyohiro Yuuki

A coding method for a two-level facsimile signal by the use of the two-dimensional coding principle, in which when successively coding addresses of a facsimile signal representative of the positions of information change picture elements, each having a binary level different from that of an immediately preceding picutre element, the above-mentioned addresses on each coding scanning line are classified into three modes that are determined by the states of information change picture elements on the coding scanning line and on a reference scanning line immediately preceding the coding scanning line. The above two-dimensinal coding principle and a one-dimensional coding principle may be adaptively adopted to shorten the transmission time and to lessen the influence of a transmission error.

Coding method for facsimile signal

A transmission method for a facsimile signal by the use of the two-dimensional coding principle, in which when successively coding addresses of a facsimile signal representative of the positions of information change picture elements, each having a binary value different from that of an immediately preceding picture element, the above-mentioned addresses on each coding scanning line are classified into three modes that are determined by the states of information change picture elements on the coding scanning line and on a reference scanning line immediately preceding the coding scanning line. The above two-dimensional coding principle and a one-dimensional coding principle may be adaptively adopted to shorten the transmission time and to lessen the influence of a transmission error.

Transmission method and system for facsimile signal

A method and apparatus for removing redundancy of scan data of pictures by coding it to reduce the transmission time or compress the transmission bandwidth. The edge states between white and black areas on the preceding line and the current line are classified into a First state in which the edge on the preceding line continues to the current line, a Second state in which the edge on the preceding line turns up on the same line, and a Third state in which the edge on the current line turns down on the same line. In the First state, the difference in the location of the edge between adjacent lines is coded; in the Second state, coding is effected only by a state code; and in the Third state, the distance between the position of the previous state and the position of the first edge and the distance between the later and the position of the next edge are coded. Since the current line can be coded only processing the preceding line and the current line one-directionally and simultaneously, implementation of a coder becomes simple. Further, since correlation between adjacent scan lines is utilized, redundancy can be effectively removed regardless of whether the document is simple or complicated.

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Yokosuka, Japan

Toyomichi Yamada