PURPOSE: To obtain a picture processing method and unit by which the capacity of a line memory can be reduced, the emphasis of an edge part or a thin line can be operated, and a picture quality can be improved.

CONSTITUTION: A pair of threshold values (x) and (y) are provided in addition to a binary threshold value which operates a black-and-white binarization. Then, objective picture elements and peripheral picture elements are compared with a pair of threshold values (x) and (y) by comparators 12 and 13, and when the picture elements and the peripheral elements are distributed so as to be increased to the upper threshold value and decreased to the lower threshold value, they are decided as the edge part by a decision part 16, and corrected.