ENCODING SYSTEM CAPABLE OF ACCOMPLISHING A HIGH EFFICIENCY BY ANTERIOR AND/OR POSTERIOR PROCESSING TO QUANTIZATION

摘要

Abstract of the Disclosure:In an encoding system responsive to a sequenceof coefficient signals which results from apredetermined linear transform and which is divided intoa sequence of blocks, anterior processing is carried outprior to quantization about the coefficient signals ineach block to determine a significant area of thecoefficient signals by comparing each level of thecoefficient signals with a threshold level. Only thecoefficient signals within the significant area arejudged to be valid and produced as a sequence ofsignificant coefficient signals from a classifyingcircuit (20) to be quantized by a quantizer (15) into asequence of quantized signals. The quantized signalsequence is subjected to posterior processing to producea sequence of encoded signals. The significant area maybe decided by the use of a selected one of zonedetection, zigzag scanning, and adaptive scanning. Inthe posterior processing, the quantized signals may beencoded into the encoded signals by the use of aplurality of code sets or tables.