Abstract: A histogram is generated by dividing pixels constituting multivalued image data loaded onto a RAM 3 into a plurality of levels. On the basis of the histogram, a level or levels are changed of at least part of the pixels of the multivalued image data. The level change enables control of the image quality of hard copy pictures. The multivalued image data, the levels of at least part of the pixels of which are changed, is converted into binary image data representing pseudo-gray levels. A printer prints the output binary image data. The hard copy picture formed on a recording medium by the printer reproduces the multivalued image data loaded onto the RAM 3 with high fidelity.