04238768 is referenced by 35 patents and cites 7 patents.

A frame of a gray-scaled picture is divided into blocks, in each of which the mean luminance of picture elements is used as a threshold value for comparison with each picture element signal to classify it into 0 or 1 according to its magnitude to provide a resolution component. From the resolution component and each picture element signal in the block are calculated two gray components; the resolution component and the two gray components are used as coded outputs for each block.

Title
Picture signal coding apparatus
Application Number
5/960542
Publication Number
4238768
Application Date
November 14, 1978
Publication Date
December 9, 1980
Inventor
Katsusuke Hoshida
Hoya
JP
Tomio Kishimoto
Yokosuka
JP
Eiji Mitsuya
Yokohama
JP
Agent
Pollock Vande Sande and Priddy
Assignee
Nippon Telegraph and Telephone Public Corporation
JP
IPC
G06K 9/00
H04N 7/12
View Original Source