frudawski

# ciexy2cct

The ciexy2cct function calculates the Correlated Colour Temperature (CCT) T_{\mathrm{cp}} from given CIE 1931 chromaticity coordinates x and y, also known as normalized tristimumuls values. Any errors in the data set or in results generated with the Lighting Toolbox are not in the liability of the CIE nor me, see licence.

Usage:

Tcp = ciexy2cct(x,y,'method')

Where:

Examples

Correlated Colour Temperature T_{\mathrm{cp}} for x = 0.3145 and y = 0.2567 using ‘Robertson’ method:

x = 0.3145;
y = 0.2567;
Tcp = ciexy2cct(x,y)

Result:

Tcp = 7511

Correlated Colour Temperature T_{\mathrm{cp}} for x = 0.3145 and y = 0.2567 using ‘exact’ method:

x = 0.3145;
y = 0.2567;
Tcp = ciexy2cct(x,y,'exact')

Result:

Tcp = 7516.7

Correlated Colour Temperature T_{\mathrm{cp}} for several chromaticity coordinates using ‘Robertson’ method:

x = linspace(0.3,0.4,5)
y = linspace(0.3,0.35,5)
Tcp = ciexy2cct(x,y,'Robertson')


Result:

x =

0.3000   0.3250   0.3500   0.3750   0.4000

y =

0.3000   0.3125   0.3250   0.3375   0.3500

Tcp =

7738   5906   4671   3825   3246


References

CIE 15:2018: Colorimetry, 4th Edition. Commission International de l’Éclairage (CIE), Vienna Austria, 2018, ISBN: 978-3-902842-13-8 , (DOI: 10.25039/TR.015.2018).

A. R. Robertson: Computation of Correlated Color Temperature and Distribution Temperature. In: Journal of the Optical Society of America, vol. 58, no. 11, pp. 1528-1535, 1968, (DOI: 10.1364/JOSA.58.001528).