The Computation of Colorimetric Purity*
Deane B. Judd · Journal of the Optical Society of America · 1926
Formulas expressing colorimetric purity in terms of given trilinear coördinates have been independently derived by Ives and Priest. This paper gives (1) the derivation of still another form of purity formula; (2) a discussion of the computational methods which are, at once, accurate and speedy, together with an analysis of the various formulas with regard to convenience for routine computing; (3) the extension of the new formulas to purity for purples; and, (4) a general solution for the trilinear coördinates (r,g,b) of a color of purity, p, in terms of the coördinates (R,G,B) of the spectrum and the luminosity coefficients (Lr, Lg, Lb).