Abstract: A system selectively enables a printer to deposit on a sheet C, M, Y and K color dots at each of the plurality of pixel locations to produce a color image. The system comprises a memory for storing C, M, Y and K color values for each pixel in the color image and a processor for controlling selective deposition of the C, M, Y and K colors. The processor determines a gray value for each pixel location from values stored in the C, M, and Y color planes. The processor subtracts the determined gray value from the C, M, and Y values which correspond to the pixel location and then determines a relationship of the gray value to a non-linear function and in dependence upon the relationship alters the C, M and Y pixel values accordingly.