In the decoding device of the coding equipment and manner and the color picture of the color picture

摘要

PROBLEM TO BE SOLVED: To obtain unified coding where reproduced image quality can optionally be controlled by receiving an RGB signal, obtaining intermediate components by the mean value of the RGB signal, the difference between G and R, and the difference between B and G, applying prediction processing to each of output components obtained from the intermediate components and applying entropy coding to the output of the prediction processing. SOLUTION: A quantizer 2 quantizes the outputs O1-O3 of a reversible color transform device 1 to respectively obtain outputs O'1-O'3. A prediction processing section 3 holds the output O'1 right in front and outputs the difference from a new output O'1 to an entropy coder 4 and uses the new output O'1 for succeeding prediction. Although the original image cannot be completely reproduced through quantization, the entropy of an output signal of the quantizer is reduced and the compression rate can be enhanced. A quantization step size controller decreases the entropy of the output signal or the power of the reproduced error under a high speed condition where distortion generated in a decoded image is suppressed within ±p with respect to the pixel value of the original image.