PURPOSE: To attain the high speed of the expansion processin from run-length data to bit map data.

CONSTITUTION: Staring point data and terminal point data composing run-length data RL are stored in a starting point counter 2 and a terminal point counter 3, respectively. The upper 11 bits of the data outputted from the both counters 2, 3 are compared in a host comparator 4 and low-order 3 bits are compared in a lower rank comparator 5. A PAL 6 loads '0' or '1' of 8-bit to a shift register 7 when UPCMP is numatched as a result of the comparison performed by the host comparator 4. Thus, an expansion speed is increased as compared with when the operation is performed by one-bit unit.