PURPOSE: To attain a high speed processing by executing a processing concerning a effective place executing segmentation when image data are segmented and processed from a sheet.

CONSTITUTION: The subject device is provided with an encoding bus 1, a direct memory accesses (DMA) 2 and 6, a decoding circuit 3, a segmenting circuit 4, a processing circuit 5, a decoding bus 7, a control part 8, and a command bus 9. When the encoded data by the DMA 2 are read from the arbitrary address of a memory, which stores the encoded image data, the read data are decoded, restored to the original image data, and the arbitrary rectangular area of them is segmented. At the segment bottom position of the image data detected by the segmenting circuit 4, the access stopping interruption is applied to the DMA 2, and a subsequent processing is stopped. Thus the high-speed processing is attained.