ciexyY2XYZ

ciexyY2XYZ

The ciexyY2XYZ function determines the CIE cone-fundamental-tristimulus values $X,Y,Z$ from CIE 1931 $x$ and $y$ chromaticity coordinates and the corresponding photometric unit $Y$ . 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 license.

Usage:

[XYZ,X,Y,Z] = ciexyY2XYZ(x,y,Y)

Where:

Parameter	Description
`XYZ X,Y,Z`	Are the CIE 1931 cone-fundamental-tristimulus values $X,Y,Z$ .
`x and y`	Are the CIE 1931 normalized cone-fundamental trisitmulus values $x$ and $y$ .
`Y`	Is the photometric unit, e.g. illuminance $E$ or luminance $L$ .

Examples

Derive cone-fundamental tristimulus values $X,Y,Z$ from CIE 1931 $x$ and $y$ coordinates and corresponding luminance $L$ :

x = 0.2165;
y = 0.4358;
L = 100;
XYZ = ciexyY2XYZ(x,y,L)

Result:

XYZ =

    49.679   100.000    79.784

Derive cone-fundamental tristimulus values $X,Y,Z$ from CIE 1931 $x$ and $y$ coordinates and several corresponding luminances $L$ :

x = 0.2165;
y = 0.4358;
L = [100:100:1000]';
XYZ = ciexyY2XYZ(x,y,L)

Result:

XYZ =

     49.679    100.000     79.784
     99.358    200.000    159.569
    149.036    300.000    239.353
    198.715    400.000    319.137
    248.394    500.000    398.922
    298.073    600.000    478.706
    347.751    700.000    558.490
    397.430    800.000    638.274
    447.109    900.000    718.059
    496.788   1000.000    797.843

Derive cone-fundamental tristimulus values $X,Y,Z$ from several CIE 1931 $x$ and $y$ coordinates and corresponding illuminances $E$ :

x = linspace(0.2,0.3,10)';
y = linspace(0.3,0.4,10)';
E = [100:100:1000]';
XYZ = ciexyY2XYZ(x,y,E)

Result:

XYZ =

     66.667    100.000    166.667
    135.714    200.000    307.143
    206.897    300.000    424.138
    280.000    400.000    520.000
    354.839    500.000    596.774
    431.250    600.000    656.250
    509.091    700.000    700.000
    588.235    800.000    729.412
    668.571    900.000    745.714
    750.000   1000.000    750.000

Derive cone-fundamental tristimulus values $X$ and $Z$ from several CIE 1931 $x$ and $y$ coordinates and corresponding illuminances $E$ :

x = linspace(0.2,0.3,10)';
y = linspace(0.3,0.4,10)';
E = [100:100:1000]';
[~,X,~,Z] = ciexyY2XYZ(x,y,E)

Result:

Reference

Bruce Lindbloom, xyY to XYZ, http://www.brucelindbloom.com/Eqn_xyY_to_XYZ.html

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