1. A method of enhancing color values of an image comprising a plurality of pixels, wherein each pixel comprises an achromatic color component value and a chromatic color component value, the method comprising: applying a continuous, monotonically increasing, non-linear function to each pixel's achromatic color component value; and for each pixel, adjusting the pixel's chromatic color component value based on a relative change of the pixel's achromatic color component value that resulted from the application of the function.