To execute prescribed work in a paste-composite picture boundary part to correct the part without a special operation by an operator.

CPU 1 extracts the boundary line of a copy source picture and a paste destination picture and also decides a picture work range based on the extracted boudary line. Then, prescribed work is executed in the picture within the picture work range based on the kind of picture work and its strength previously set in paste setting memory 2-3 and, then, display and an output is executed.