[Foundation of a linear trichromatic transfer theory on color judgment of unsaturated colors].
On a visual tristimulus colorimeter, normal trichromatic subjects applied the perceptual criteria "neither blue nor yellow," "neither green nor red", and "heterochromatically equally bright" to unsaturated colours in order to construct an opponent colour space. Such an opponent colour space is related to the instrumental colour space defined by the colorimeter. By introducing a fundamental colour space and a set of physical colour stimuli, physiologically relevant transfer equations are established and demonstrated on various spectral efficiency functions.