PURPOSE: To improve the compression effect by coding and to enhance picture quality at an intermediate tone area without deterioration of resolution of a character and a line drawing.

CONSTITUTION: A picture read by a picture reader is extracted in a photoelectric conversion element block extract section 11 by using 2×2 picture elements as one block and a difference arithmetic operation section 12 obtains a difference between picture element data in the block. A total sum processing section 13 calculates the total sum of picture element levels in the block. Then A comparison processing section 16 compares the difference with a prescribed threshold level and a selection section 17 selects either a high resolution binarizing processing section 14 using the total sum and each picture element data to apply binarizing processing with the same resolution as the read picture or a low resolution binarizing processing section 15 using the total sum and using one block as one picture element to implement binarizing processing depending on the result of comparison and the selected result is outputted from a picture element output section 18.