United States Patent [19] [ii] Patent Number: 4,831,659
Miyaoka et al. [45] Date of Patent: May 16, 1989
[54] METHOD FOR IMAGE DATA CODING
[75] Inventors: Shinichiro Miyaoka, Kawasaki;
Ryoichi Sasaki, Fujisawa; Takayoshi
Shiraishi, Chigasaki, all of Japan
[73] Assignee: Hitachi, Ltd., Tokyo, Japan
[21] Appl. No.: 208,851
[22] Filed: Jun.7,1988
Related U.S. Application Data
[63] Continuation of Ser. No. 923,854, Oct. 28, 1986, abandoned.
[30] Foreign Application Priority Data
Oct. 28, 1985 [JP] Japan 60-241218
[51] Int. C1.+ G06K 9/00
[52] U.S. CI 382/56; 358/260
[58] Field of Search 382/56, 27; 358/260,
358/263
[56] References Cited
U.S. PATENT DOCUMENTS
4,205,341 5/1980 Mitsuya 358/260
4,222,076 9/1980 Knowlton 358/260
4,231,095 10/1980 Cassagne 358/260
4,261,018 4/1981 Knowlton 358/260
4,319,267 3/1982 Mitsuya 358/260
4,520,506 5/1985 Chan 382/56
4,691,329 9/1987 Juri 382/56
Primary Examiner—Leo H. Boudreau
Attorney, Agent, or Firm—Antonelli, Terry & Wands
[57] ABSTRACT
To efficiently compress image data, the image data is divided into rectangular blocks of non-equal length in a hierarchal structure in accordance with a brightness change, and is encoded into tree-structure data for each of the divided blocks so that the mean distortion of the image data inside each block does not exceed an allowable value.
3 Claims, 12 Drawing Sheets
