CODEWITHSUNDEEP
rgbmultimediacolor-spacecolor-theory
xiaoting cai
xiaoting cai

Reputation: 61

Why there is no brown or grey in the CIE XY color space?

Why there is no brown or grey in the CIE XY color space?

Upvotes: 2

Views: 3708

Answers (2)

Kel Solaar
Kel Solaar

Reputation: 4090

One has to be really careful on the terminology: XY upper-case doesn't exists in colour science, the closest term would be CIE XYZ tristimulus values.

If you were referring to the CIE 1931 Chromaticity Diagram used to represent xy chromaticity coordinates, then it should written xy lower-case.

The CIE 1931 Chromaticity Diagram and all other chromaticity diagrams are usually drawn with colours at their maximum Luminance value. That being said, nothing prevent one to compute the chromaticity diagrams colours with a Luminance value different from 1 (100%) which would allow you to have greyish / brownish colours.

It is important to note that you can't actually properly display the visible spectrum colours as they are outside sRGB colourspace gamut. Thus any colour outside sRGB triangle is incorrectly represented and sometimes you find chromaticity diagrams where the diagram colours have been altered (saturation lowered essentially) to fit within sRGB colourspace gamut.

I'm adding an animated GIF so that you can see that the diagram is a 2d projection of the CIE xyY colourspace seen from the top.

CIE xyY

Upvotes: 5

Mark
Mark

Reputation: 92461

The xy chromaticity graph isn't a color space; it's a two dimensional projection of a color space designed to separate hue and saturation from luminosity. To represent gray and brown you need this third dimension since grey is basically dark white and brown is dark orange. A 3 dimensional color space like xyY where Y is a third dimension representing luminosity has no trouble with grey and brown. In this case gray values would extent down from the white point and browns would extend below the orange.

Upvotes: 8

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