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:
| Parameter | Description |
spec | Is a vector containing the reconstructed spectral daylight distribution. |
lam | Is a vector containing the spectral wavelength: default: 300 nm – 830 nm in 5 nm steps. |
xd | Returns the corresponding CIE 1931 chromaticity x coordinate(s). |
yd | Returns the corresponding CIE 1931 chromaticity y coordinate(s). |
cct | Specifies the Correlated Colour Temperature (CCT) T_{cp} in K, scalar or vector. |
lam | Is a vector defining the wavelengths. Default: 300:5:830 |
Y(optional) | Defines the integral weighted target value derived from the spectral power distribution. |
W(optional) | Defines the weighting function for the integral target value (see above). Default: 'VL' for the V(\lambda) weighted photopic value. |
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]
See also: plotspec
Note: plotspec only displays the visible range from 380 nm – 780 nm.
Result:
ans = 0.2990 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)
See also: ciespec2Y
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')
See also: ciespec2Y, ciespec2unit
Result:
Y = 1.0000e+04 1.2314e+07 mel = 1.3262e+01 1.5000e+04
Reference