frudawski

# ciecct2spec

The ciecct2spec function calculates the corresponding spectral daylight distribution for a given Correlated Colour Temperature (CCT) T_{cp} in K, according to the CIE procedure described in CIE 15:2018 Colorimetry, 4th Edition. The returned spectral range is given from 300 nm to 830 nm in 5 nm steps. 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:

[spec,lam,xd,yd] = ciecct2spec(cct,lam,Y,W)

Where:

Examples

Derive and plot the daylight’s spectral power distribution (SPD) for a CCT of 7500 K:

cct = 7500;
[spec,lam,xd,yd] = ciecct2spec(cct);
plotspec(lam,spec)
[xd,yd]

Note: plotspec only displays the visible range from 380 nm – 780 nm.

Result:

ans =

0.2991   0.3150

Create spectral power distribution of D75 with resulting photometric value of |Y| = 10000:

lam = 380:780;
spec = ciecct2spec(7500,lam,10000);
Y = ciespec2Y(lam,spec)

Result:

Y = 10000

Create spectral power distribution of ‘D65’ and ‘D5634’ with different target values and weighting functions:

lam = 360:830;
spec = ciecct2spec([6500 5634],lam,[10000 15000],{'VL','mel'});
Y = ciespec2Y(lam,spec)
mel = ciespec2unit(lam,spec,'mel')

Result:

Y =

1.0000e+04
1.2318e+07

mel =

1.3259e+01
1.5000e+04

Reference

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).