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Significance Statement
A daylight-like illuminant based on the spectral power distribution (SPD) of complementary colors was first suggested in R.W.Pridmore (2009), “Double helix structure of illuminant whites,” AIC Congress 2009, Sydney). In that and the present article, a graph of the SPD was extended from the visible spectrum to the full hue circle (as in Munsell and CIE color spaces) by use of a nominal wavelength scale for the nonspectral purples, so as to clarify the helix structure, as shown in the Figure on this page (see Fig. 5 in the 2013 Color Res. & Applic. article).
A recent article (O. Masuda and S.M.C. Nascimento (2013), “Best lighting for naturalness and preference,” Journal of Vision, 13(7):4,1-14), tested various spectral compositions for daylight illuminants and found that observers preferred those with SPDs typical of complementary colors, that is, with spectral peaks about 490 nm (cyan), 570 nm (yellow), and the two ends of the spectrum (representing a combined peak in magenta).
Journal Reference
Color Research & Application, Volume 38, Issue 4, pages 292–296, 2013.
Ralph W. Pridmore.
Macquarie Centre for Cognitive Science, Macquarie University, Sydney, NSW, Australia
Abstract
I report a curious double helix in psychophysical data. As recently reported, color complementarism structures at least 40 functional roles in vision including all Red-, Green-, Blue-peaked functions (e.g., color matching functions, Helmholtz–Kohlrausch effect, saturation discrimination, lightness discrimination, and wavelength discrimination). These can be modeled from the relative spectral power distribution (SPD) function of complementary colors (at requisite power ratios to neutralize complements). So, the SPDs three-dimensional (3D) structure is of interest. Extended to the hue cycle, the SPD is plotted in a rectilinear graph of wavelength versus wavelength with radiance vertical to the plane. In this rectilinear color mixture space, the white locus representing the illuminant chromaticity is not a single point (representing the junction of complementary pairs of wavelengths) but a sinusoidal curve whose 3D structure is a double helix, representing an SPD and its complementary SPD. The structure’s purpose is possibly to store and access global complementary colors data across illuminants. © 2012 Wiley Periodicals, Inc. Col Res Appl, 38, 292–296, 2013
Copyright © 2012 Wiley Periodicals, Inc.
