APPENDIX B
CIE Color Measurement System
To determine a standard observer, a set of red, green, and blue lamps is used by a number of representative subjects to match all the pure colors of the spectrum. The result is called a set of color-matching functions. The set of color-matching functions for the Commission Internationale de l’Éclairage (CIE) standard observer is illustrated in Figure B.1. They were obtained with red, green, and blue pure spectral hues at 700, 546, and 436 nanometers, respectively, using a number of trained observers. Notice that there are negative values in these functions. These exist for the reasons discussed in Chapter 4. It is not possible to match directly all spectral lights with these, or any other, primaries.
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