Patent · US Expired

Method and apparatus for adaptive transform coding of picture signals

US4225885A · kind A · utility

19Cited by

7References

5Claims

0Family size

Assignee

U.S. Philips Corporation · US

Inventors

Peter Lux · Hamburg, DE
J/rgen Petzold · Hamburg, DE

Key dates

Filing date	Feb 13, 1978
Grant date	Sep 30, 1980
Priority date	—
Expiry date	Feb 13, 1998

Classification

Technology area (CPC H)Electricity
CPC primaryH04N19/60
WIPO fieldAudio-visual technology
WIPO sectorElectrical engineering

Abstract

A method and apparatus to reduce the redundancy for the transmission or storage of picture signals using transforms. The basis coefficients are arranged in a sequence and thereafter quantized in the customary manner. The basis coefficients obtained from the transformation are sequentially examined to see if they exceed a predetermined value, for example the average value across the entire picture. The number of times the value is exceeded is counted. If, in a sequence class, the number of coefficients exceeding the predetermined value is more than half the total number in the sequence class then the associated sequences are quantized with a larger number of bits. For this purpose, activity classes are formed which indicate which sequences in the picture are active and the characteristic of the quantizer is controlled by this class information.

Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.