IMAGE DATA COMPRESSION DEVICE, COMPRESSION METHOD, PROGRAM, AND IMAGE DATA DECOMPRESSION DEVICE, DECOMPRESSION METHOD, AND PROGRAM

摘要

A quantizer quantizes a "prediction error" as a difference value between a pixel X to be compressed and a prediction value X'. A variable-length encoder inputs a quantization number obtained from a quantization table of the quantizer, and outputs a variable-length code (compressed code).
A prediction value candidate calculation module calculates candidates 1 through k for a prediction value on the basis of peripheral pixels A, C, and B, and transmits them to a multiplexer (MPX). A prediction value determination module determines a prediction value among the candidates 1 through k for a prediction value on the basis of an intermediate value correspondence table and an intermediate value - image format correspondence table depending on an image format, and transmits a control signal to the multiplexer (MPX). The multiplexer (MPX) outputs one of the candidates 1 through k for a prediction value as a prediction value X'. Thus, by appropriately using a prediction value depending on the image format, the prediction error of each image format can be reduced.