LOSSLESS COMPRESSION-ENCODING DEVICE AND DECODING DEVICE FOR IMAGE DATA

In a lossless compression-encoding device, a calculation part calculates differences between different types of pixel data representing the first, second and third color components of an image, and outputs the calculated differences as a plurality of types of difference data. A lossless compression-encoding part performs lossless compression-encoding on each of color component data which include the different types of the pixel data representing the first to third color components and the plurality of the types of the difference data, and outputs a plurality of types of compressed data which correspond to the respective types of the color component data. A comparison and selection part compares amounts of data of the plurality of the types of the compressed data obtained from the lossless compression-encoding, and selects a combination of three types of compressed data corresponding to three types of color component data capable of synthesizing the respective pixel data representing the first, second and third color components such that a total amount of data of the selected combination is smaller than a total amount of data of other combinations of the compressed data.