Image data for a page having an amount of data exceeding the capacity of a printer memory is suitably output. A comparison is made among areas of buffer management blocks (TIME) in four data queues in which cyan, magenta, yellow, and black image data commands are stored. Then, the image data command having the earliest time is selected and is transferred to a printer. As a result, the image data is transferred in the order in which it is to be output in the printer.