Trichromatic system

The CIE system is a trichromatic system its basis is the fact that any color can be... 

X, Y, and Z are the tristimulus values of a light, i.e. they are the amounts of three reference stimuli needed to match exactly the light under consideration in a trichromatic system. 

In matching colors by reference to three primaries, we are dealing in a trichromatic system. The X Y Z tristimulus values of C.I.E. space are created by simple linear transformation of the color space of B G B. Given any second system, JB, the two may be related thus ... 

CIE System. The name derives from the initials of the Commission Internationale de I Eclairage. It is a trichromatic system of colour notation that is used, for example, in the glass industry. 

The most successful quantitative expression of color is that known as the CIE (Commission Internationale de l Eclairage) system [13]. This methodology assumes that color may be expressed as the summation of selected spectral components (blue, green, and red hues) in a three-dimensional manner. The CIE system is based on the fact that human sight is trichromatic in its color perception, and that two stimuli will produce the same color if each of the three tristimulus values (X, Y, and Z) are equal for the two. Detailed summaries of the CIE and other quantitative systems for color measurement are available [14,15],... 

Colorimetry [1.17] - [1.19]. The principles of colorimetry are based on the fact that all color stimuli can be simulated by additively mixing only three selected color stimuli (trichromatic principle). A color stimulus can, however, also be produced by mixing the spectral colors. Thus, it has a spectral distribution, which in the case of nonluminous, perceived colors is called the spectral reflectance q (2). After defining three reference stimuli, the trichromatic principle allows a three-dimensional color space to be built up in which the color coordinates (tristimulus values) can be interpreted as components of a vector (CIE system for standards, see Table 1, Colorimetry CIE = Commission Internationale de l Eclairage). For uncolored illumination the three CIE tristimulus values depend on the spectral reflectance as follows ... 

Hoglund, G. Hamdorf, K. Rosner, G. (1973) Trichromatic visual system in an insect and its sensitivity control by blue light. J. Comp. Physiol, vol. 86, pp. 265-273... 

All the wavelengths of the spectrum must be capable of being matched by mixtures of the red, blue, and green stimuli to which the eye responds. These proportions have been measured with trichromatic colorimeters at 5 m,u intervals over the spectral range by a number of different observers. The average values are used to specify the responses of the hypothetical Standard Observer and they can, by mathematical treatment, be converted into the chromaticity co-ordinates of the C.I.E. system. 

Because cone vision is trichromatic, it means a suitable mixture of red, green and blue primary lights, as would be expected from a three-receptor system, can... 

Thus, a color is characterized by three numbers, X, Y, and Z, and, consequently, can be shown as a point in a three-dimensional coordinate system. Since each kind of color may be defined by its color proportion, or what is known as the standard color value proportion (trichromatic coefficient), and, by definition, the sum of all the trichromatic coefficients is unity, then, the color can be shown as a point in a two-dimensional diagram. This diagram is also known as the chromaticity diagram or color table (Figure 14-8). The line joining the points at 400 and 700 nm is called the purple line. Thus, all real colors lie within the horseshoe structure in Figure 14-8. 

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