cieuv2cct

cieuv2cct

The cieuv2cct function calculates the Correlated Colour Temperature (CCT) $T_{\mathrm{cp}}$ from given CIE 1960 chromaticity coordinates u and v, also known as Uniform Colour Space (UCS). See also: ciexy2cct. 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 = cieuv2cct(u,v,'method')

Where:

Parameter	Description
`Tcp`	Is a scalar or vector containing the resulting Correlated Colour Temperature(s) (CCT) in K.
`u and v`	Are the input scalars or vectors containing the CIE 1960 chromaticity coordinates $u$ and $v$ .
`'method' (optional)`	Specifies the determination method: ‘Robertson’: (default) Robertson’s calculation algorithm, formerly the only recommended algorithm by the CIE. This method is fast and quite accurate. ‘exact’: shortest distance method as described in CIE 15:2018, very accurate but comparably slow. Results may vary with different implementation methods. Both methods return NaN if the colour coordinates lie outside the meaningful interval of $\Delta uv < 0.05$ from the planckian locus in CIE 1960 chromaticity diagram.

Examples

Correlated Colour Temperature $T_{\mathrm{cp}}$ for $u = 0.2308$ and $y = 0.2825$ using the default ‘Robertson’ method:

u = 0.2308;
v = 0.2825;
Tcp = cieuv2cct(u,v)

Result:

Tcp = 7513

Correlated Colour Temperature $T_{\mathrm{cp}}$ forr $u = 0.2308$ and $y = 0.2825$ using ‘exact’ method:

u = 0.2308;
v = 0.2825;
Tcp = cieuv2cct(u,v,'exact')

Result:

Tcp = 7519.3

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

u = linspace(0.25,0.30,5)
v = linspace(0.25,0.30,5)
Tcp = cieuv2cct(u,v,'Robertson')

Result:

u =

   0.2500   0.2625   0.2750   0.2875   0.3000

v =

   0.2500   0.2625   0.2750   0.2875   0.3000

Tcp =

   50060    7679    3202    2498    2169

References

CIE 15:2018: Colorimetry, 4th Edition. Commission Internationale de l’Eclairage (CIE), Vienna Austria, 2018, ISBN: 978-3-902842-13-8 , (DOI: 10.25039/TR.015.2018. URL: https://cie.co.at/publications/colorimetry-4th-edition

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. URL: https://opg.optica.org/josa/viewmedia.cfm?uri=josa-58-11-1528&seq=0

Leave a Reply Cancel reply