fundamental stimulus

fundamental stimulus (In French stimulus de base) model for identifying a color perception on a value basis, resulting from the physiological measurement of the luminous efficiency of the retinal receptors (cones) responsible for daytime vision. From the Greek numbering of the 1st (proto), 2nd (deutero) and 3rd (trito) cone type come the designations of the fundamental stimuli P (cone releasing green dye, therefore recently also called M as in midwave), D (cone which is luminously efficient in the blue-green area, but which releases red dye, therefore also called L as in longwave) and T (cone releasing blue dye, therefore also called S as in shortwave), which are characterized by their respective spectral value functions p, d, t. Their color values PDT represent chromaticity coordinates in the fundamental stimulus system, the basis for all other color stimuli and color stimuli systems (RGB, CIEXYZ).