PURPOSE: To enable character synthesis in which the color and density of a character for a character original and a halftone original can be preserved to be performed and especially, to apply this editor widely to the aspect of design.

CONSTITUTION: Memory 307 stores a first color separation image signal, and an area generating part 308 reads out the first color separation image signal from the memory 307, and when a second color separation image signal is inputted synchronizing with the above readout, one of the first or second color separation image signal inputted based on input is selected, and a third color separation image signal can be generated based on a selected color separation image signal, and a generated third color separation image signal is stored in the memory 307.