A method for optimizing colored images emitted by a color printer on the
non-white surfaces of substrates and for optimizing the amounts of
printing ink used, wherein an image motif is processed by a
computer-assisted image processing system in order to form a master copy
which is ready for output. The method determines, for each pixel, whether
and with what color density, a white underprint can be applied to a
corresponding pixel, using an algorithm based on overall color density
S.sub.F. The surface of the substrate is thus only underprinted with white
on the pixels of the master copy where the overall color density is
lacking or low.
