Methods and systems herein provide for color conversion. Such color conversion includes a method of optimizing gray component replacement in a color image that includes receiving a color image from an input imaging device (e.g., a digital camera, scanner, etc), determining a color gamut of an output imaging device, such as a printer, and generating a CIELab to CMY numerical model to convert the color image to a color space within the color gamut of the output imaging device. The method also includes generating a CMYK to CIELab numerical conversion model, removing a portion of CMY color values generated from the CIELab to CMY numerical conversion model, and replacing the removed portion of the CMY color values with black color values. The method also includes optimizing CMYK color values via a multidimensional optimization using the CMYK to CIELab numerical model.