N.P.L. Colour-matching Investigation: Final Report (1958)

Abstract The second part of the N.P.L.'s colour-matching investigation was devoted to determining average colour-matching properties in a large (10° diameter) bipartite matching field, and the final corrected results are here presented in tabular form, together with a specification of the conditions of measurement, and ancillary data on repeatability. The tabulated results comprise (a) mean colour-matching functions, referred to reference primaries at wave-numbers 15 500, 19 000 and 22 500 cm-1, for spectral stimuli in the range 12 000 to 25 500 cm-1, given at intervals of 250 cm-1 between 16 000 and 22 000 cm-1 and at intervals of 500 cm-1 outside these limits, (b) the standard deviations and correlation coefficients of the colour-matching functions at wave-numbers between 14 000 and 25 500 cm-1, (c) mean colour-matching functions corrected for rod intrusion in the range 12 000 to 17 000 cm-1, (d) the corresponding mean unit coordinates in a W.D.W. system, and their standard deviations, (e) the mean relative luminosity factors of the reference primaries and their standard deviations determined by both direct-comparison and flicker heterochromatic matching, (f) the mean relative luminosity function V λ in the range 12 000 to 15 000 cm-1 determined by direct comparison with 14 250 cm-1. The main colour-matching results are based on 49 subjects, but the results for spectral stimuli of wave-number less than 14 000 cm-1 rest on fewer subjects. The extent to which the results show an increase with age in the yellow pigmentation of the eye is discussed.