Reflectance Spectra of Munsell Standard Chips and Their Appearance

In this article, we present the results of analysis by two different methods for representing information in reflectance spectra of Munsell standard chips that relates to their appearance. The spectrum of a chip j is denoted as rjl where l represents wavelength k from 430 to 660 nm with 1 nm intervals. The spectrum of light reflected from a chip j under D65 is rjl 3 el where el represents the spectral power distribution of D65 illumination. In one method, singular value decomposition is applied to a matrix of (rjl 3 el). Combining results of this analysis with results of human assessment experiments, we obtain four curves n0a(H) that represent principal hue components a in Munsell Hue, a 1⁄4 redness, yellowness, greenness, and blueness (Fig. 6). The other method is multiple regression of each (rjl 3 el) to activities of three kinds of cones in the retina. From this analysis, we obtain three curves Bq(H) that represent relative involvements of q 1⁄4 L, M, S cone activities in determining the appearance of Munsell Hue (Fig. 10). Two sets of curves, n0a(H), and Bq(H), are compared with predictions from a model of higher order color mechanism (Fig. 12) that has been proposed on the basis of experiments with light stimuli of wavelength k. It is found that n0a(H), and Bq(H) constructed from broadband spectra of Munsell chips are interpretable in terms of this model. 2008 Wiley Periodicals, Inc. Col Res Appl, 33, 229–237, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20406