Ralph L Nichols

US Patent:

47046287, Nov 3, 1987

Filed:

Jul 16, 1986

Appl. No.:

6/886634

Inventors:

Wen-hsiung Chen - Sunnyvale CA
James P. Elliott - Cupertino CA
Robert E. G. Newell - San Jose CA
Ralph E. Nichols - Los Gatos CA
Albert E. Rackett - Sunnyvale CA

Assignee:

Compression Labs, Inc. - San Jose CA

International Classification:

H04N 712
H04N 7133
H04N 7137

US Classification:

358136

Abstract:

An apparatus and method for signal processing employing intraframe and interframe variable prediction transform coding. Images are represented by sequential frames of two-dimensional arrays of digital signals. The digital signals are transformed to form transform coefficients for each frame. Predicted transform coefficients are formed using sets of variable prediction factors. The predicted transform coefficients for each frame are compared with corresponding actual transform coefficients for the frame to form transform coefficient difference signals. The difference signals are processed to control their range of values. The processed difference signals are statistically coded such that the more frequently occurring values are represented by shorter code lengths and the less frequently occurring values are represented by longer code lengths. The coded signals are stored in a buffer memory for transmission.