JPS647789A - Noise shaping predictive encoding system - Google Patents

Abstract

PURPOSE:To reduce quantization enthropy, to improve the quality of an encoding image, and to reduce the number of transmission bits by correcting a predictive error value by using a noise shaping filter value based on the magnitude ration between an evaluation value which is the absolute differential value between preliminarily encoded picture elements and a prescribed threshold. CONSTITUTION:Preliminarily encoded picture element information is stored in a memory part 30, an evaluation value generation part 31 generates an evaluation value D from the adjacent picture element values stored in the part 30, and thus obtained value is compared with a prescribed threshold Th. At the time of correcting a predicted error value obtained by a predictive error generation part 21 by means of a shaping filter value obtained by a noise shaping filter 26, in case of D<Th (difference between picture element values is small), a predictive error value is corrected with a value from the filter 26 then is quantized based on a quantization representative value by a predictive error quantization part 23, however, if D>=Th, the predictive error value is directly quantized, thus the value is encoded. By such a constitution, quantization enthropy is reduced, the quality of coded image is improved in result, and the number of necessary transmission bits are reduced.