Convert the XYZ [1] tristimulus values to standard CIE 1931 xyY coordinates with Equations 4 – 6:. The example power spectrum shown in Figure 1d has coordinates of (x = 0.224, y = 0.702, Y = 7.179) ...

It measures the illuminance (in lux) from the light source as well as the visible spectrum (380-780nm), correlated colour temperature (CCT, Kelvin), CIE chromaticity (xy), CIE tristimulus values (XYZ) ...