CIE Chromaticity Explorer

Select a colour using any of the coordinate systems, the CIE 1931 chromaticity model, the CIE 1960 UCS, the CIE 1976 UCS, or with Tcp and Δuv. Lock/Unlock the reticle on the CIE models by clicking on the graph. Observe how the coordinates interact with each other as they describe a colour.

CIE 1931 (xy)
CIE 1960 UCS (uv)
CIE 1976 Luv (u'v')
Colour Temperature
ESTA E1.54 16-bit DMX
CIE 1931 (xy) CIE 1931 xyY

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Colour Temperature



CIE 1960 UCS (uv) CIE 1960 UCS (uv)

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CIE 1976 Luv UCS (u'v') CIE 1976 Luv UCS (uv)

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Glossary

Chromaticity
An objective specification of the quality of a color regardless of its luminance.
CCT
See Tcp
CIE
The International Commission on Illumination (usually abbreviated CIE for its French name, Commission internationale de l'éclairage) is the international authority on light, illumination, colour, and colour spaces. It was established in 1913 as a successor to the Commission Internationale de Photométrie and is today based in Vienna, Austria.
CIE 1931 (x,y)
The first defined quantitative links between distributions of wavelengths in the electromagnetic visible spectrum, and physiologically perceived colors in human color vision.
CIE 1960 UCS (u,v)
The CIE 1960 UCS is mostly used to calculate correlated color temperature, where the isothermal lines are perpendicular to the Planckian locus. As a uniform chromaticity space, it has been superseded by the CIE 1976 UCS.
CIE 1976 Luv (u',v')
A CIE colour space which attempted perceptual uniformity. Additive mixtures of different colored lights will fall on a line in this model's uniform chromaticity diagram (dubbed the CIE 1976 UCS). Unless the mixture is of constant lightness, this is true only for the chromaticity diagram and not the CIELUV colour space.
v′ is 1.5 times as large as v its 1960 predecessor.
Chromaticity difference can be calculated as the Euclidean distance of the u'v' coordinates of two colours.
Δuv
How close (length of the hypotenuse) the Tcp of a u,v coordinate is to the Planckian locus. The CIE only considers values to be meaningful within Δuv = ±5×10-2.
Positive values are +green, negative values are +magenta.
ESTA E1.54
Specifies a standardized color space and defines the locations of the RGB primaries and the White Point for the purpose of facilitating the communications between lighting controllers and color‐changing luminaires. The method is generic and is neither manufacturer‐specific nor color technology‐specific.
The Arri Skypanel conforms to this communications standard, begining with firmware 3.0, for both calibrated RGB and x,y coordinate modes.
Planckian locus
The path that the color of an incandescent black body would take in a particular chromaticity space as the blackbody temperature changes.
Robertson's Method
A method to estimate the correlated color temperature by way of interpolation from look-up tables and charts. Robertson's method takes advantage of the relatively even spacing of the mired scale to calculate Tcp using linear interpolation of the isotherm's mired values.
Tcp
The correlated Planckian temperature (CCT, Tcp) is the temperature of the Planckian radiator whose perceived color most closely resembles that of a given stimulus at the same brightness and under specified viewing conditions -- CIE/IEC 17.4:1987, International Lighting Vocabulary (ISBN 3900734070)
Although the CCT can be calculated for any chromaticity coordinate, the result is meaningful only if the light sources are nearly white. Beyond a certain value of Δuv, a chromaticity co-ordinate may be equidistant to two points on the locus, causing ambiguity in the CCT.
UCS
A chromaticity diagram which attemps to have uniform spacial distance between coordinates of equal color distance.