References
- One set, for example, is prepared by the U. S. Department of Transportation, specified by the Code of Federal Regulations, Title 49—Transportation. The set dates from January 1973. Each color, complete with six tolerance limits, is supplied in the form of a “hazardous materials label and placard.” Another set is specified by the American National Standards Institute.
- The percent of luminance reflected, compared to a perfect diffuser at 100 percent.
- By W.L. Heaps, member of the IES Color Committee.
- LeGrandYves, Light, Colour and Vision, 2nd Edition, London: Chapman Hall, Ltd., 1968, p. 58.
- Notwithstanding the high tabulated values of percent purity of the Y, O, R colors under the high pressure sodium lamp, the perceived colors of Y, O, R are quite unsaturated. While perceived color is thus not in accord with what one might expect from the “percent purity” values, it is in accord with distances on the color diagram, which must be at least approximate measures of magnitude of perceived color-difference. In recent decades, perhaps because of excesses in interpretation of the color diagram in its early history, some experts have fallen into the practice of overemphasizing the dangers in such interpretation; today one can hear it said that the color diagram has nothing whatever to say about perceived color. In fact, the color diagram serves very well, up to a point, in suggesting what perceived color is to be associated with a given chromaticity. It is always necessary to establish the “white point” (the chromaticity of the illuminant); but from that point, the dominant wavelength gives a good idea of perceived hue; and distance from the white point, a good idea of the perceived saturation of a color.
- As established by the IES Color Committee.
- ThorntonW. A., “Luminosity and color-rendering capability of white light”, Journal of the Optical Society of America, Vol. 61, No. 9, September 1971, p. 1155.
- ThorntonW. A., “Fluorescent lamps with high color-discrimination capability”, Journal of the Illuminating Engineering Society, Vol. 3, No. 1, October 1973, p. 61.