1. A system for processing color image data including first and second color separations, each color separation including an array of pixels, the system comprising: a gray level spacing circuit receiving a first input gray level for a first color separation pixel and a second input gray for a second color separation pixel, the gray level spacing circuit identifying first upper and lower bounding gray levels and second upper and lower bounding gray levels, each of the first upper bounding level and first lower bounding level corresponding to one of j multi-level output values for the first color separation wherein 2<j, the first upper bounding level and first lower bounding level defining a range of gray levels that includes the first input gray level and has a first gray level spacing, each of the second upper bounding level and second lower bounding level corresponding to one of k multi-level output values for the second color separation wherein 2<k, the second upper bounding level and second lower bounding level defining a range of gray levels that includes the second input gray level and has a second gray level spacing; a level scaling circuit receiving a first modified gray level for the first color separation pixel and a second modified gray level for the second color separation pixel, the level scaling circuit scaling the first modified gray level to a common level spacing in relation to the first gray level spacing to generate a first scaled gray level and scaling the second modified gray level to the common level spacing in relation to the second gray level spacing to generate a second scaled gray level; and a quantization circuit receiving the first and second scaled gray levels and deriving a first multi-level output value for the first color separation pixel and a second multi-level output value for the second color separation pixel based on a sum of the first scaled gray level and the second scaled gray level.