PURPOSE: To improve the efficiency of the whole processing by shortening the free time of an image information read task (scanner task) greatly.

CONSTITUTION: This method includes a GSP task 3 which displays image information on a display, the scanner task 4 which reads the image information, an UCDA task 5 which compresses or expands the image information, and an SCSI task 6 which registers or reads image data out. The processing task 4 for the image read while using a necessary number of free buffers secured by a control task 2 reads image information of plural pages without any idle time according to commands from the control task. Simultaneously, the respective processing tasks 3, 5 and 7 for the image information processing performs processing such as the display and compression of the image information read out to the buffers. Consequently, the idle time of the image information read processing is eliminated substantially, so the time of the whole processing can be shortened.