An image forming apparatus and method arranged to perform a process in which a copyright code is set as electronic watermark information in red, green, and blue image data obtained by a scanner, the image data is then transferred to a printer to undergo density conversion with respect to yellow, magenta, cyan, and black, and a printer serial number is set as electronic watermark information in the converted image data, followed by printing of the image data. This process facilitates discrimination of the two items of information.