IMAGE DATA CODING SYSTEM FOR CONTROLLING AMOUNTS OF CODE DATA FOR CHARACTER IMAGE AND NATURAL IMAGE REGIONS

An image coding device capable of securely controlling a total code amount to a fixed amount in coding image data including a character image region and a natural image region mixed together. The image coding device includes a first circuit for extracting a character image region having a variable size from input image data; a second circuit for controlling a code amount of image data of the character image region; a third circuit for multivaluing image data of the character image region extracted by the first circuit; a fourth circuit for reversible coding image data of the character image region multivalued by the third circuit; a fifth circuit for subtracting the image data of the character image region from the input image data to generate image data of a natural image region; and a sixth circuit for non-reversible coding the image data of the natural image region generated from the fifth circuit; wherein the size of the character image region to be extracted by the first circuit is controlled by the second circuit so that the code amount of the image data of the character image region becomes a first preset target code amount, and the image data of the natural image region is coded by the sixth circuit so that a code amount of the image data of the natural image region becomes a second preset target code amount.