The image coding operates by dividing an image into multiple regions on the basis of predetermined sub-division criteria. The regions are integrated with adjacent regions under a predetermined rule for integrating regions, and these integrated regions are encoded. The integration criteria imply a comparison between the execution of a coding with a given region composed with the adjacent regions and the execution of the coding without the region composed with adjacent regions. A provisional encoder performs a preliminary encoding, and a distortion calculator provides information to evaluate the provisional encoding.
