MATCHING COLOR IMAGES - THE EFFECTS OF AXIAL CHROMATIC ABERRATION

We show how to compute and to use the wavelength-dependent optical transfer function (OTF) to create color matches between spatially patterned images. We model the human OTF as a defocused optical system with a circular aperture. In our model the defocus arises from axial chromatic aberration and wavelength-independent aberrations. From the computed OTF it is apparent that high-spatial-frequency components of the image can play little role in contrast and color appearance and that in the spatial-frequency range from 5 to 20 cycles/deg the visual system is dichromatic, because there is no contrast in the short-wavelength receptor signal. We show how to use the wavelength-dependent OTF to match color images across displays by setting matches in corresponding spatial-frequency bands. Because chromatic aberration so affects the OTF, this new procedure is a significant improvement over the conventional procedure of setting matches point by point.