To embed a copyright code into R, G, and B image data read by a scanner as electronic water mask information before transmitting it to a printer, to concentration-circuit is into Y, M, C, Bk, and to embed a printer equipment number as electronic water mark information before printing it out out to easily identify those two information.

A copyright code is embedded in the R signal of image data photographed by an image scanner part 201 as water mark information, and this signal is processed and transmitted to a printer part 202. Then, this signal is concentration-converted into a Y, M, C, and Bk signal, and the equipment number of the printer is embedded as yellow water mask information. The R copyright code is concentration-converted into C(cyanogen) so as to be easily identified from the yellow equipment number.