PURPOSE: To provide a picture resolution converting processor without the generation of moire by making only a character image definite and smoothing a dot picture.

CONSTITUTION: An edge judging part 5 judges whether an attentional picture element is in the vicinity of a linear edge or not from the input picture data of plural picture elements around the attentional picture and a 1st interpolating processing part 2 calculates a picture element value on an optional picture element position by interpolating the input picture data. A high band emphasis part 3 executes the clearing processing of the input picture data an a 2nd interpolating processing part 4 inputs and interpolates the output of the emphasis part 3 and calculates a picture element value on the same picture element position as that of the 1st interpolating processing part 2. An adder 8 executes the weighting operation of the results of the 1st and 2nd interpolating processing parts 2, 4 in accordance with the degree of existence of the remarked picture element in an edge area by means of the output of the edge judging part 5.