Towards an improved uniform color space

Abstract

Analysis of the Munsell, the OSA-UCS, and the NCS systems shows that the idea, originally introduced with the Adams–Nickerson color space and difference formula, that the Munsell value function not only applies to the tristimulus value Y but also to X and Z, is inaccurate. For all three systems, different power functions are required for X and Z. In the case of Z, different powers are needed for the yellow and blue halves. An additional correction is required for the curvature of the constant hue lines of blue colors. New a and b formulas are introduced that correct these shortcomings of CIELAB. In a hue scaling experiment with Munsell chips, the Munsell hue scale was found inaccurate, and a different number of equal-sized hue steps was found in some of the four quadrants. The implications for color difference calculation are discussed. © 1999 John Wiley & Sons, Inc. Col Res Appl, 24, 253–265, 1999