PURPOSE: To expand or contract the whole or part of a picture optionally, by dividing an original picture into areas and performing picture-element density conversion basing on a projecting method on the basis of relating equations arranged to the respective areas.

CONSTITUTION: An original picture element plane is divided into eight areas. When part of the original picture element plane is cut and expanded or contracted, the center of the plane to be cut is denoted as R. The plane cut centering on R overlaps with the original picture element plane. Then, the mean value of weighting is obtained while weighting corresponding to the overlap area ratio of respective areas is considered. The mean value of weighting is varied according to the position of R. Original picture element information is substituted in the expression of the mean value of weighting to obtain new picture element information.