Color receptor

The values of x, y, and z published by the CIE are presented in Figure 3 y(X) is also the luminosity response function. As discussed above, these curves can loosely be regarded as the eye response curves of red, green, and blue color receptors in the eye. For greatest effectiveness, a phosphor s emission spectrum has to match these curves well to yield both the proper color and maximum brightness. Of the two components of rare earth phosphors, the host largely determines efficiency while the activator determines the emission spectrum. 

Green-colored receptor/transporter Red-colored receptor/transporter... 

The answer to this question apparently comes from the sensitivity of the receptors themselves. Each receptor has a broad range of sensitivity, being most sensitive to one particular input value and less sensitive to other input values, with the degree of sensitivity becoming smaller as the difference from the most sensitive input value becomes greater. With several of these receptors, each with a different maximum sensitivity, perception can be related to the combination of outputs from different receptors. Thus, we may see different colors that do not correspond to the maximum sensitivities of any of the color receptors. Tactile localization could occur as long as the output frequencies of the skin touch sensors vary with distance from the receptor loeation. 

Age-related macular degeneration accounts for about half of all registerable visual impairments in the United Kingdom. It typically results in the loss of central vision (see Figure 41.1). Since most of the color receptors are in the macula (the central area of the retina), those with macular degeneration see colors less vividly. 

In summary, the tristimulus values are orientated according to the average sensitivity of the human eye. Light with a different spectral distribution may have the same effect on the three color receptors in the human eye. This will result in the perception of the same color. 

Many things were of interest to Maxwell, and he published papers on a wide range of topics (his first at the age of 14). He studied optics and optical properties of materials, and he developed the fish-eye lens. One of Maxwell s interests and areas of investigation was color vision. He projected the first color photograph, and he explained color blindness as a deficiency in one or two of the three types of color receptors in the eye. He was interested in the stability of the earth s atmosphere and its thermodynamics and in stress in building frameworks. 

Moreover, multivariate optimization, the simultaneous optimization of several properties, will increasingly come into focus. A drug should have high selectivity in binding to different receptors and minimal toxicity, good solubility and penetration, and so on. A hair color should have a brilliant shine, be absorbed well, not be washed out, not damage the hair, not be toxic, and be stable under sunlight, etc. 

Olfactory receptors have been a subject of great interest (9). Much that has been postulated was done by analogy to the sense of sight in which there are a limited number of receptor types and, as a consequence, only three primary colors. Thus attempts have been made to recognize primary odors that can combine to produce all of the odors that can be perceived. Evidence for this includes rough correlations of odors with chemical stmctural types and the existence in some individuals having specific anosmias. Cross-adaptation studies, in which exposure to one odorant temporarily reduces the perception of a chemically related one, also fit into this hypothetical framework. Implicit in this theory is the idea that there is a small number of well-defined odor receptors, so that eventually the shape and charge distribution of a specific receptor can be learned and the kinds of molecular stmctures for a specified odor can be deduced. 

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 right-reading positive image resides on the receptor film after lamination, exposure through a positive, and wash-out of the unexposed areas with a solvent or aqueous developer. The four-color proof is built up by the sequential lamination, exposure, and development steps. 

Full-color printing requires pages be reprinted three or four times in registration. Receptors pass over the printhead several times at exactiy the same speed and location, but contact a differentiy colored section of donor. A fourth pure black color can improve dark picture regions, sharpen text and line art, and mask color misregistration. 

Transfer occurs by sublimation, condensation, and diffusion (101). Printhead thermal dissipation causes donor dye to travel to the surface of the donor ribbon and convert directiy to a gas. Colorant puffs immediately strike the nearby receptor and soak in, assisted by residual printhead heat. 

Any color signal received from the snbject will be rated by the spectral sensitivity of the eye. The physiological bases for this are three types of cone-shaped receptors on the human retina that are sensitive to red, green, and bine. The color measurement techniques have been established on this tri-colorimetric system. They simulate human perception by the relative extent to which the observer estimates the relative share of which of these three components contributes to his color impression from an object. 

The leuco dyes of this new class are peculiar in that they are capped at their 10-position by another dye moiety. They are in fact colored leuco dyes which on oxidation are split into two different dye fragments one of the dyes is destined for the receptor sheet while the oxidized leuco hopefully remains on the donor sheet. The capping dye is selected among sublimable dyes whereas the azine dyes being cationic in nature would be less mobile. They have been developed to address some problems encountered in thermographic and photothermographic systems.24 Representative examples of this class of leuco dye developers are compounds 65, 66, and 67. 

Pressure-sensitive recording materials are obtained by dissolving a triphenylmethane leuco dye in a solvent composed of paraffin oils. The microcapsules are formed from a water-soluble106 or water-dispersible material.107,108 Leuco dyes dissolved in sunflower oil are microencapsulated in a solution containing a melamine-HCHO precondensate and coated on the back side of a paper sheet. Contact of the microcapsule-coated sheet with an acid-coated receptor sheet allows the color formation to occur. 

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