COMPRESSION AND EXPANSION (QUANTIFICATION) OF DIGITAL DIFFERENTIALLY ENCODED TELEVISION SIGNALS

摘要

1. A process of compression and expansion (quantification) of DPCM digital differentially encoded television signals, wherein the values of the thresholds and reconstruction levels are varying according to the prediction value Pn relative to the current point to be encoded, the range of variation of the prediction value Pn being divided into prediction zones Zi where i varies from 1 to k, a set of values of thresholds and reconstruction levels Qi being associated with each prediction zone Zi , said set being invariable for all values Xn of the sample to be encoded, the prediction value Pn of which is included in the zone Zi , said set varying from a zone Zi to another, each set Qi having the same number N of values of thresholds and reconstruction levels, with negative and positive extreme values of thresholds and reconstruction levels which are different from one prediction zone Zi to another, characterized in that the prediction zones Zi are non-symmetrical with respect to the dynamic average of the prediction value Pn .