Trichromats

Color and Color Separation. In 1860,James Clerk MaxweU discovered that all visible colors could be matched by appropriate combinations of three primary colors, red, green, and blue (RGB). His experiment involved mixtures of colored lights added together to produce other colors or white light. This additive color is weU represented by the primaries RGB. Indeed, human color vision is trichromatic, ie, human visual response approximates receptors for the colors recognized as red, green, and blue (see Color). 

The trichromatic theory, subsequendy confirmed by the existence of the three sets of cones, must be combined with the opponent theory, which is involved in the retinal pathway. A third approach, the appearance theory (2) or the retinex theory, must be added to explain color constancy and other effects. As one example of this last, consider an area perceived as red in a multicolored object such as a Mondrian painting when illuminated with white... 

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],... 

Since color is a perceived quantity, a strict mathematical relation relating tristimulus values to a concept of color is not possible. An equation has been proposed, however, that relates the perception of a color to these values. The trichromatic equation for tristimulus values is normally put into the general form... 

Gilad, Y., Wiebe, V., Przeworski, M., Lancet, D and Paabo, S. (2004) Loss of olfactory receptor genes coincides with the acquistion of full trichromatic vision in primates. PloS Biology, 2, 120-125. 

Trichoderma reesi, 12 479, 480 Trichoderma viride, 10 536 Trichothecene mycotoxins, 14 144, 146 Trichromatic sources, for white LEDs, 14 862... 

Trichromatic theory, of color, 7 304, 308 Tricinnamate chiral stationary phase, 6 88t Trickle-bed reactor, 21 333-334 Trickling filter... 

The ink jet printing of coloured images is a subtractive process and requires a YMC trichromat as in colour photography. Some of the properties required in the dyes are listed below. 

Many of these dyes suffer from poor wet fastness and light fastness properties, especially in the magenta shade area, or they are not the right shade for the desired trichromat. 

To achieve full-colour displays it is necessary to have efficient low MW OLEDs that emit in the red, green and blue areas of the spectrum. Intensive research in this field has shown that this requirement can be met by careful selection of the ET host and loading this with the correct amount of a specific dopant, although there is a tendency for lower quantum efficiency. Some examples of the types of the emitters and host/dopants that produce the RGB trichromat are illustrated in Table 3.13. 

Heredia, F.J. and Guzmanchozas, M., The colour of wine — a historical-perspective. 2. Trichromatic methods, J. Food Quality, 16, 439, 1993. 

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 ... 

Cerium magnesium aluminate is a highly efficient green phosphor (lmax. = 541 nm), which is used in trichromatic fluorescent lamps. The high quantum yield of 65 % is effected by the energy transfer from the sensitizer, Ce3 +, to the activator, Tb3 +. ... 

The phosphor LaP04 Ce3+, Tb3+ has assumed importance as the green component in trichromatic fluorescent lamps. The emission maximum is at 544 nm and the... 

Sr3(P04)2 SrCl2 Eu2+ can be excited by radiation from the entire UV range. The excitation maximum lies at 375 nm and the emission maximum at 447 nm. Upon successive substitution of Sr2+ by Ca2+ and Ba2 +, the emission maximum shifts to 450 nm. In the preparation, SrCl2 is used in excess to improve the crystallization [5.378], The phosphor was used as the blue component in trichromatic fluorescent lamps [5.379] and in the first generation of compact lamps. 

In practice, the fur dyer does not differentiate between these two dye classes. Dye manufacturers offer a selected color range with compatible anionic dyes including the suitable auxiliaries. Consequently the recommended optimized dyeing conditions should be monitored closely. As a rule, the trichromatic dyeing technique is applied, in which the standard colors blue, red, and yellow are mixed to obtain the desired shade. 

Figure 5.5.9-3 shows both the individual functional spectra of long-wavelength trichromatic vision, and the nonfunctional dipole-molecular spectra of the same molecules, in caricature on a linear relative ordinate versus wavelength. This technique allows the information of the figure to be interpreted more easily. However, note that most of the actual data from the laboratory involves a logarithmic ordinate. The ultraviolet spectrum related to R(5) has been omitted for convenience on this graph. 

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