Method for image data coding

• US 4,831,659 A
• Filed: 06/07/1988
• Issued: 05/16/1989
• Est. Priority Date: 10/28/1985
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Sasaki, Ryoichi, Shiraishi, Takayoshi, Miyaoka, Shinichiro
• Primary Examiner(s): Boudreau, Leo H.
• Application Number:
  US07/208,851
• Time in Patent Office: 343 Days
• Field of Search: 382/56, 382/27, 358/260, 358/263
• US Class Current: 382/240
• CPC Class Codes: G06T 9/40 Tree coding, e.g. quadtree, octree
• CPC Class Codes: H04N 19/96 Tree coding, e.g. quad-tree coding

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.

Claims

1. A method of encoding image data, comprising the steps of:

dividing said image data into blocks of variable size so that an index representing the degree of an error, generated by approximation of the data in each block by a polynomial function of at least two independent variables corresponding to the coordinates on said image data multiplied respectively by a predetermined coefficient, is less than a predetermined value;

quantizing the coefficient of said function;

encoding said quantized data in a form of treestructured data.

2. A method of encoding image data according to claim 1, wherein said index is a mean square error of the data representing brightness of a pixel in each block.

3. A method of encoding image data according to claim 1, wherein said function is a linear function of two independent variables multiplied respectively by a predetermined coefficient.