Towards an improved uniform color space

Analysis of the Munsell, the OSA-UCS, and the NCS systems shows that the id ea, originally introduced,vith the Adams-Nickerson color space and differen ce formula, that the Munsell value function not only applies to the tristim ulus value Y but also to X and Z, is inaccurate. Fbr all three systems, dif ferent power functions are required for X and Z. In the case of Z, differen t powers are needed for the yellow and blue halves. An additional correctio n is required for the curvature of the constant hue lines of blue colors. N ew a and b formulas are introduced that correct these shortcomings of CIELA B. In a hue scaling experiment with Munsell chips, the Munsell hue scale wa s found inaccurate, and a different number of equal-sized hue steps was fou nd in some of the four quadrants. The implications for color difference cal culation are discussed. (C) 1999 John Wiley & Sons, Inc.