Nikon 9235 Reference Manual - Page 114
combining red and blue light., closed by these lines are created by mixing light of different
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Profiles can be further classified according to their gamut, or the range of colors that can be expressed using the profile. Gamut is conventionally expressed by means of chromaticity, a measure of color developed by the Commission Internationale de l'Éclairage (CIE). The CIE system, which is modeled on human color perception, maps the physical wavelengths of light to three coordinates (known as CIE X,Y, and Z) that give unique numerical expression to the full range of color differences that can be perceived by humans. Chromaticity is a measure of color from which considerations of brightness have been factored out, giving a two-coordinate system. In the chromaticity diagram at right, the complete gamut of colors visible to humans is in the area enclosed by the green line. The curved portion of the line gives the chromaticity of "pure," unmixed colors with wavelengths in the visible spectrum of 380- 780 nm. The blue end of the spectrum (380 nm) is at the bottom left corner, the red end of the spectrum (780 nm) at the bottom right corner. The straight diagonal line connecting these two points represents the different shades of purple created by combining red and blue light. The colors inside the area enclosed by these lines are created by mixing light of different wavelengths. No color profile is capable of expressing the full range of colors visible to the human eye. The diagram below compares the gamut of colors visible to the eye with the colors that can be expressed in each of the RGB profiles provided with Nikon CMS. The gamut for each profile is contained in the triangle defined by the three points that mark the extremes of red, green, and blue for that profile (red is at the bottom right corner, green at the top of the triangle, and blue at the bottom left corner). The white point for each profile is shown by the symbol in the center of the triangle. y 1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 x 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Apple RGB Color Match RGB sRGB NTSC (1953) Bruce RGB Adobe RGB (1998) CIE RGB Wide Gamut RGB Human Reference: Preferences 113