color stimulus

color stimulus (In French stimulus de couleur) 1) physical identification of the light radiation which, through direct stimulation of the cones (retinal receptors) causes a perception which can be felt as color. The color stimulus can come from a primary radiator (light source) as well as from a secondary radiator (remitting surface). 2) identification in terms of value of chromaticity coordinates in the color space with the help of a vector pointing from the coordinate origin 0 to the chromaticity coordinates (localized vector). The vector is formed through the addition of for example vectors rR, gG, bB. A distinction is made between primary stimuli R, G, B (additive color mixture), basic stimuli P, D, T (description of daytime vision, adaptation and color vision deficiency by means of the 3 cone types PDT and recently LMS) and virtual standard stimuli X, Y, Z (CIEXYZ, description of all colorimetric phenomena).