Spectrum of the color samples We measured the spectrum of the color samples using four kinds of illuminants: CIE Standard Illuminant A, Cool White, Daylight, and Horizon. Here is the information of the soccer field in Stockholm. Color temperature : 3400 kelvin Illumination : 600 - 700 lux The Correlated Color Temperature(CCT) of these four are as follows: - CIE Standard Illuminant A 2900K - Cool White 4266K - Daylight 7042K - Horizon 2324K We also measured the Spectrum of illuminants themselves using the reference white board.