PURPOSE: To reduce the degradation of a picture due to printing of the machine body number, the copy date, or the like.

CONSTITUTION: A Fourier transform circuit 105, a filter 106, a Fourier inverse transform circuit 107, a picture processing circuit 108, and a picture memory 110 extract the high frequency component based on color picture data inputted from a scanner 101. An add-on circuit 103 synthesizes inputted color picture data and color picture data indicating the copying machine body number and the copy time in the area of the extracted high frequency component.