Riemannian color difference metric for spatial sinusoidal color variations.

Several studies report on the sensitivity of human vision to static spatial sinusoidal achromatic and chromatic contrast variations. However, a Riemannian color difference metric, which includes the spatial and colorimetric properties of sinusoidal gratings, is lacking. Such a metric is important for various applications. Here we report on the development of a new Riemannian metric, for the prediction of detection ellipsoids in color space, for spatial sinusoidal gratings as a function of the grating's size, spatial frequency, luminance and chromaticity. The metric is based on measurements and models of achromatic and isoluminous chromatic contrast sensitivity functions available in literature, and the Riemannian metric for split fields which we reported earlier. We find adequate agreement with various data sets of experimental achromatic and isoluminous chromatic contrast sensitivity functions and with experimentally determined threshold ellipses of isoluminous chromatic Gabor gratings.