| object colour stimuli that correspond to objects whose luminance factors have maximum possible values for each chromaticity when their spectral luminance factors do not exceed unity for any wavelength
Note 1 to entry: Optimal colour stimuli correspond, in general, to objects whose spectral luminance factors have values of either unity or zero, with not more than two transitions between them.
Note 2 to entry: The luminance factors and chromaticity coordinates of optimal colour stimuli define the boundaries of a colour solid corresponding to non-fluorescent objects.
Note 3 to entry: For a given luminance factor, optimal colour stimuli define the maximum purity possible for non-fluorescent objects.
Note 4 to entry: See also "object colour", "colour stimulus".
Note 5 to entry: This entry was numbered 845-03-40 in IEC 60050-845:1987.