US Patent 7508557 System and method for processing a multi-colour image

A system and method are provided for processing digital multi-color images for the reproduction thereof on a color printing and/or copying device provided with a plurality of process colors defining a gamut. The system includes a color processing module, which divides the gamut into multiple sub-gamuts, each defined by three chromatic process colors, and which selects for each pixel of the digital multi-color image the corresponding sub-gamut. For each pixel it is judged whether or not to add a non-white achromatic process color or blue to the process colors defining the corresponding sub-gamut.