A controller for a four-drum printer eliminates a need for an expensive inter-drum delay memory, which has been conventionally used, to print an RGB image and allows a multifunction machine, printer, and the like to be provided at low cost. An image ring interface reads an image data containing the same tile, which is stored in a tile pattern in a RAM, four times with a delay corresponding to a delay (10 lines of tiles) of image formation between image forming sections, and sequentially transfers the image data to four image output interfaces.