lecture13-2

Combined the cie commission internationale declairage

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Unformatted text preview: o 500 nm cannot be generated cannot CIE Color Space No standard set of three wavelengths can be No combined to generate all other wavelengths. combined The CIE (Commission Internationale d’Eclairage) The CIE defined three hypothetical lights X, Y, and Z with these spectra: these Idea: any wavelength λ can Idea: be matched perceptually by positive combinations positive of X, Y, and Z of x~R y~G z~B CIE Color Space The gamut of all colors perceivable is thus a threeThe gamut dimensional shape in X, Y, Z Color = xX + yY + zZ CIE Chromaticity Diagram (1931) For simplicity, we often project to the 2D plane x+y+z=1 x = x / (x+y+z) y = y / (x+y+z) z=1–x-y Device Color Gamuts Since X, Y, and Z are hypothetical light sources, Since no real device can produce the entire gamut of perceivable color perceivable Example: CRT monitor Device Color Gamuts We can use the CIE chromaticity diagram to We compare the gamuts of various devices: compare Note, for example, Note, that a color printer that cannot reproduce all shades available on a color monitor A Problem With XYZ Colors If we have two colors C1 and C2, and we add ∆ C If to both of them, the differences between the original and new colors will not be perceived to not be equal be This is due to the variation of the just noticeable This differences in saturated hues differences XYZ space is not perceptually uniform XYZ perceptually LUV space was created to address this problem RGB Color Space (Color Cube) Define colors with (r, g, b) amounts of red, green, Define and blue and RGB Color Gamuts The RGB color cube sits within CIE color space The something like this: something Converting Color Spaces Simple matrix operation: R ' XR G ' = YR B ' ZR XG YG ZG XB R YB G ZB B The transformation C2 = M-12 M1 C1 yields RGB on The monitor 2 t...
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This note was uploaded on 01/23/2012 for the course CS 445 taught by Professor Bloomfield,a during the Spring '08 term at UVA.

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