Decomposition of Cohen's matrix R into simpler color invariants.

Matrix R of linear-group tristimulus invariants, presented by Cohen and Friden (1976) and Cohen and Kappauf (1982), was decomposed into functions of simpler tristimulus volume ratios (also linear-group invariants). Such volume ratios were applied to the dual problems of color constancy and illuminant-invariant object-color recognition by an artificial trichromatic photosensor. The proof of the decomposition theorem relies on a lemma used in previous work elucidating the conditions for illuminant-invariance of clockwise/counterclockwise ordering of triads of object colors in chromaticity space.