Distance metrics for very large color differences

Small, supra‐threshold color differences are typically described with Euclidean distance metrics, or dimension‐weighted Euclidean metrics, in color appearance spaces such as CIELAB. This research examines the perception and modeling of very large color differences in the order of 10 CIELAB units or larger, with an aim of describing the salience of color differences between distinct objects in real‐world scenes and images. A psychophysical experiment was completed to compare directly large color‐difference pairs designed to probe various Euclidean and non‐Euclidean distance metrics. The results indicate that very large color differences are best described by HyAB, a combination of a Euclidean metric in hue and chroma with a city‐block metric to incorporate lightness differences.