The technique of the invention sets a first image plane 70 having an information volume per pixel set to 4 bytes and a second image plane 72 having the information volume per pixel set to 1 byte. The area of each image plane is set to a printing area. Full color images are drawn on the first image plane 70, whereas characters and simple illustrations are drawn on the second image plane 72. The technique combines the first image plane 70 with the second image place 72 to a composite image plane, further lays an operation image plane 74, which has the information volume per pixel set to 4 bits and is used to display information required for a device operation, upon the composite image plane to a composite display window 76. RGB data is output to display the composite display window 76 on a monitor. The contents of the first image plane 70 and the second image plane 72 are described in a script. The technique of the invention analyzes the script and prints generated images based on the results of the analysis.