REVERSIBLE IMAGE COMPRESSION DEVICE, METHOD THEREFOR, REVERSIBLE SYSTEM IMAGE RESTORING DEVICE AND METHOD THEREFOR

摘要

PROBLEM TO BE SOLVED: To efficiently encode, even image data of an image of excessively changing luminance, and to compress the image data at high compressibility. SOLUTION: An occurrence frequency table is made for each luminance value of the reference pixel of original image data, to calculate the occurrence frequency of the luminance value of a target pixel, encoded tables are made every luminance value of the reference pixel from the result of the calculated occurrence frequency, the optimum encoded table is selected from among a plurality of the encoded tables for each every luminance value of the reference pixel, and the target pixel is encoded in the code row corresponding to the attentional pixel, using the selected encoded table.