The contrast-sensitivity function (CSF) is a measure of fundamental spatiochromatic properties of the human visual system. It is typically measured at the detection threshold for the psychophysically defined cardinal channels: luminance, red-green, and yellow-blue. Recent measurements of luminance contrast sensitivity show that the sensitivity of the luminance channel is less for chromatic stimuli than for achromatic stimuli. This chromatic effect has important implications for both human and machine vision. The chromatic effect on luminance contrast sensitivity has been modeled in this work based upon an existing model published by Barten. Barten's model was chosen as the starting point for this work because it is analytical, relatively simple, and can predict those effects that are important for image analysis. (C) 2006 Wiley Periodicals, Inc.