frudawski

# ciespec2wp

The ciespec2wp function determines the white point of an illuminant’s spectral power distribution. 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:

[XYZ,xyz] = ciespec2wp(lam,spec,observer)

Where:

Examples

Whitepoint of CIE standard illuminant ‘A’, ‘E’ and ‘D65’:

lam = 360:830;
spec = ciespec(lam,{'A','E','D65'});
[XYZ,xyz] = ciespec2wp(lam,spec)

Result:

XYZ =

1.0984   1.0000   0.3559
1.0001   1.0000   1.0003
0.9505   1.0000   1.0888

xyz =

0.4475   0.4074   0.1450
0.3333   0.3333   0.3334
0.3127   0.3290   0.3582


Whitepoint of CIE standard illuminant ‘A’ for 10° standard observer:

lam = 360:830;
spec = ciespec(lam,'A');
[XYZ,xyz] = ciespec2wp(lam,spec,'xyz10')

Result:

XYZ =

1.1114   1.0000   0.3521

xyz =

0.4511   0.4059   0.1429


Determine the tristimulus values X,Y,Z for standard illuminant ‘D65’ with an resulting photometric value of Y = 15000:

lam = 360:830;
spec = ciespec(lam,'D65');
XYZ = ciespec2wp(lam,spec).*15000

Result:

XYZ =

1.4257e+04   1.5000e+04   1.6332e+04


Determine and plot the whitepoint of an artificial spectral power distribution (SPD):

lam = 380:780;
% create a linear decreasing SPD
spec = linspace(1,0,numel(lam));
[~,xyz] = ciespec2wp(lam,spec)
plotciexy(xyz(1),xyz(2))

xyz =
0.2762   0.2916   0.4322
ISO/CIE 11664-1:2019(E): Colorimetry - Part 1: CIE standard colorimetric observers. Commission International de l’Éclairage (CIE), Vienna Austria, 2019.
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).