primary stimuli, primaries

primary stimuli, primaries (In French stimulus de couleur de référence) mathematical model for the value-based identification of a color stimulus in additive color mixing; derived from the basic stimuli of the 3 cone types, the real color stimuli R, G, B characterize the color signal absorption in the 3 color channels of the eye; CIE(1931) definitions of the primary stimulus wavelengths λ and the related relative spectral radiation distribution S(λ) for the equi-energy spectrum (illuminant E) and the 2° standard observer: λR = R = 700.0 nm and S(700) = 72.096; λG = G = 546.1 nm and S(546.1) = 1.379; λB = B = 435.8 nm and S(435.8) = 1. Technical definitions of primary stimuli are for example the color filters in a color scanner or the subpixel colors of LCD monitors.