Color rendering, a reassessment

Color Research and Application

Volumn 24, Issue 3, 1999, Pages 197-206

  Van Trigt, C ^a  

^a NONE   (Netherlands)

Author keywords

Chromatic adaptation; CIE; Color rendering; Light sources

Indexed keywords

EID: 0001053704     PISSN: 03612317     EISSN: None     Source Type: Journal    
DOI: 10.1002/(SICI)1520-6378(199906)24:3<197::AID-COL6>3.0.CO;2-S     Document Type: Article

References (15)

1. Method of measuring and specifying colour rendering properties of light sources. Publication CIE no. 13.2. Bureau Central de la CIE: Paris, 1974.
2. Equivalently, the parts played by the reference and test source may be interchanged in this sketch of the method. Thus, the corresponding color may be defined as the color whose appearance under the test source corresponds to that of the test-color sample under the reference source (see Ref. 3). The procedure in the text is, for subtle reasons, to be preferred and is, in any case, the one of Ref. 1, as can be inferred from the formulas.
3. Wyszecki G, Stiles WS. Color science: concepts and methods, quantitative data and formulae. 2nd Ed. New York: Wiley; 1982.
4. Ouweltjes JL. private communication to the author; 1988.
5. Ouweltjes JL. The general colour-rendering index, its meaning and its use. Colour 73 London: Adam Hilger; 1973.
6. It was realized that this was hard to maintain generally. A weaker assumption viz. that the color rendering is the best possible, is made in Ref. 5. In the discussion, we must adhere to the formal definitions. If these have unpleasant consequences, this does not mean that the authors were not aware of (some of) them, but could not find a satisfactory solution.
7. In the section "Explanatory comments" of Ref. 1, it is stated that the index is not an absolute figure. Hence, the reference should be mentioned. This is annoying and has not been prescribed, probably for this reason. Not surprisingly, this proviso tends to be forgotten. Furthermore, observers seem to possess some absolute standard (in memory) by which the color rendering of a source is judged. If so, a relative standard is of little interest.
8. van Trigt C. Visual system response functions and estimating reflectance. J Opt Soc Am A 1997;14:741-755.
9. Finlayson GD, Drew MS, Funt BV. Spectral sharpening; sensor transformations for improved color constancy. J Opt Soc Am A 1994;11: 1553-1563.
10. van Trigt C. Color video system with illuminant-independent properties. International patent application PCT/NL94/00049 (February 28, 1994).
11. Thornton WA. Evidence for three spectral responses of the normal human visual system. Col Res Appl 1986;11:160-163.
12. We ignore that the original method uses U*V*W* space, this being irrelevant to the discussion. Meanwhile, CIE TC 1-33 has replaced the space with L*a*b*.
13. Robertson AR. The CIE 1976 Color-difference formulae. Color Res Appl 1977;2:7-11.
14. MacAdam DL. Metric coefficients for CIE color-difference formulas. Color Res Appl 1985;10:45-49.
15. Brill MH, West G. Chromatic adaptation and color constancy: a possible dichotomy. Color Res Appl 1986;11:196-204. This article presents spectral conditions on the reflectance (and spectral distribution) functions such that the von Kries type quotient is strictly illuminant-independent. They are not realistic, supporting that this cannot be achieved.