PURPOSE: To simultaneously increase work areas and multi-level image areas, to set optimum memory capacity and to reduce useless memory capacity by providing the work areas and multi-level image areas of a CPU not as independent memories but on the same memory.

CONSTITUTION: A CPU 100 controls the entire device, and the control program or fixed data of the CPU 100 is built in a ROM 103. A RAM 102 is provided with an area for storing the output information for each color and the work area of the CPU 100. A memory write/read circuit 101 executes the read/write control of the RAM 102, and a data input part 104 inputs data such as character information or the like. Although the CPU 100 sets data to a register, corresponding to the data set here, the work area and the multi-level image area are automatically divided. Therefore, the work area and the multi-level image area can be easily separated, and the memory can be precisely and easily increased.