IMAGE COMPRESSION METHOD, IMAGE RESTORATION METHOD, PROGRAM, AND APPARATUS

摘要

An image compression is performed as follows. An input image is divided into blocks of a predetermined number of pixels in the vertical and horizontal directions. The divided blocks are scanned in the main scan direction and sub-scan direction and successively selected as a processing block. A block in the positional relationship and pixel value relationship with the selected block satisfying a predetermined condition is selected as a reference block. Subsequently, the pixel value of the processing block is exclusively OR-ed (XOR) with the pixel value of the reference block to generate a difference image. When the difference image satisfies a predetermined condition, the processing block is replaced by the difference image. Furthermore, an image including the difference image obtained by the block replacement in the processing block is coded and the code data obtained by executing this image coding, replacement/non-replacement to a difference image of each processing block obtained by executing the block replacement, and positional information of the reference block are combined and output. An image restoration is performed as follows. An image including a difference image is decoded from code data. The processing block in which this decoded image is divided into blocks is exclusively OR-ed (XOR with the reference block to decode the original image.