CIE METHOD FOR CALCULATING TRISTIMULUS VALUES

The new recommendations state that the standard method of performing the integration forming the basic definition of tristimulus values shall be by summation at a wavelength interval of 1 nm over the wavelength range 360-830 nm, but that for most colorimetric purposes the approximation of summation at a 5-nm interval over the range 380-780 nm should suffice. Recognizing that measured data fulfilling these requirements are not usually available, recommendations were also made concerning abridgement, interpolation, extrapolation, truncation, and the calculation of weighting factors. This article describes the recommendations, now accepted by the CIE and providing clear and complete guidelines for the uniform calculation of CIE tristimulus values.