The (<i>U</i>*, <i>V</i>*, <i>W</i>*) system has been checked against the Munsell renotation system on the assumption that the latter provides an equispaced visual scale. As the result of the examination, it has been found that the formula for lightness index is in excellent agreement with the Munsell value function, in spite of its numerically simplified form and that the value effect appearing on the CIE 1960 UCS diagram is over corrected by making the chromaticness indexes depend upon the first power of <i>W</i>*. Twenty five times the ⅚-power of <i>W</i>* has been found to be more suitable for the weighting factors to be applied to the chromaticness indices. The value effect has been reduced to about 4570 by the use of the modified chromaticness indices. On the basis of the modified system, a formula is proposed for computation of color differences for pairs of similar colors. In addition, a formula is proposed for specifying whiteness for practical purposes, based on the modified system.
MASAXO SATO and RYUICHI HIOKI, "Modification of the (U*, V*, W*) System," J. Opt. Soc. Am. 59, 349-354 (1969)