ENCODER AND DECODER

In the encoding/decoding system, when encoding an image, the image encoding device (100) divides the encoding-target image into several subimages, and executes the encoding on the subimages in a direction moving away from the boundary of the divided subimages. In addition, when executing the encoding process, the image encoding device (100) transmits pixels in the vicinity of the boundary of the subimages as uncompressed data, without encoding the pixels. Furthermore, when executing an encoding process, the image encoding device (100) changes quantizing steps that are used in the encoding in accordance with a distance from the boundary so that an amount of data greater than or equal to a predetermined value can be assigned for the vicinity of the boundary by use of smaller quantizing steps.