What's CIE1931 chromaticity Coordinate x, y ?
In daily life we will say to help me buy a red color clothes, but what kind of "red" pink pink pink???? red? So people use chromaticity diagram (Chromaticity Diagram), using three dimensional three axis position to represent a color.
In a system as the color coordinates, you tell me a color coordinates, each individual can accurately understand you want what color is the color of the human eye. L, M, S and the formation of a cone, the eye of R, G, B color reaction, must do a series of color matching experiments (color matching experiment), through these experiments to get eye parameters on the reaction of different wavelength, the wavelength of different colors by using the human response can be corresponding to a color to a coordinate, and coordinate with color.
In 1931, the International Commission on illumination (CIE, Commission International de L Eclairage = 700.00nm) using optical wavelength, the wavelength of light (representing the crimson) = 546.1nm (Huang Lvshai), = 435.8nm (with purple and blue light wavelength) of monochromatic light as RGB color stimuli (primary stimulus). The experiment can understand, almost any color can be used for specific the primary colors together. The visible light (380nm ~ 780nm) in each 10nm segment, 380 10inm, i = 0,1, 39. Repeat tests, as the primary colors of light together, for example, with 10nm as a spacer, each monochromatic light (i.e. 100% color saturated light) matching equation, said for the matching function (color matching, function, CMF). So each R, G, B as a unit vector composed of three dimensional axis, so that any one of the three F color space, the color space (color space).
CIE chromaticity diagram is three dimensional because of trouble, at the same time through additive colour mixing, we learned that light color and color of R, G, B ratio is related to the CIE in 1931 in the development of the RGB system at the same time, and to determine the original stimulus the new value of X, Y, Z, the XYZ color. XYZ color system is also known as the CIE 1931 color system (CIE 1931 standard colorimetric system).
CIE-RGB and CIE-XYZ change, hope in the new coordinate system, only one stimulus value Y represents the brightness, and unlike the CIE-RGB system in R, G, B values all contribute to the brightness, and the formation of a new color map, X, Y, Z that is representative of the new chromaticity diagram. The three primary colors the color is not as virtual, so CIE-XYZ chromaticity diagram is very convenient but only a virtual chromaticity diagram.
1931 CIE Chromaticity Diagram (from http://www.ledtronics.com)
CIEXYZ Color matching factor is ¯x (λ), ¯y (λ), ¯z (λ)
- For (λ) spectra, the tristimulus is as follows
- Converting the XYZ to chromaticity coordinates