Select a colour using any of the coordinate systems, the CIE 1931
chromaticity model, the CIE 1960 UCS, the CIE 1976 UCS, or with
T_{cp} and Δ_{uv}. 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.

- It is important to remember that colours used in the backgrounds of the CIE models are representativ only. The device being used to display this page is capable of reproducing only a subset of the visible chromaticity gamut.
- The MacAdam Ellipse drawn on the CIE 1931 graph is flawed. It is calculated as quadratic curves from the quadrants of a circle on the CIE 1976 graph. In CIE 1976, a circle is only an approximation of the MacAdam Ellipse. It is drawn with an arbitrary radius of 0.01

- Chromaticity
- An objective specification of the quality of a color regardless of its luminance.
- CCT
- See T
_{cp} - 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 As a uniform chromaticity space, it has been superseded by the CIE 1976 UCS.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.
- Δ
_{uv} - How close (length of the hypotenuse) the T
_{cp}of a u,v coordinate is to the Planckian locus. The CIE only considers values to be meaningful within Δ_{uv}= ±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 T
_{cp}using linear interpolation of the isotherm's mired values. - T
_{cp} - The
__c__orrelated__P__lanckian temperature (CCT, T_{cp}) 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 Δ
_{uv}, 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.