Bezold–Brucke hue-shift as functions of luminance level, luminance ratio, interstimulus interval and adapting white for aperture and object colors

UNLABELLED For spectral and nonspectral aperture color 3 s stimuli, Bezold-Brucke (B-B) hue-shift was measured for one to six subjects for four functions: (1) luminance (L) level from 0.1:1.0 through 100:1000 cd/m2; (2) L ratio from 1:2 through 1:1000; (3) illuminant color temperature (for seven illuminants including A and D65) by two adaptation methods; and (4) interstimulus interval from 0 through 40 s; the latter removes contrast effects and inverts hue-shift, so B-B 'invariants' become hue-shift maxima. SUMMARY four wavelengths are 'invariant' for a given L level or ratio. With higher L level, invariants shift as opposed pairs: to longer wavelength for b and y, shorter for g and r. With higher L ratio, b and y invariants shift some 10 nm longer but g and r remain about 508 nm and 493.5 c. With higher illuminant color temperature, invariants (1:10 cd/m2) shift shorter for b and y, r slightly longer (spectral to nonspectral 494 c) but g seems constant. Hue-shift data for real object color are very similar to aperture color. The full hue cycle is graphed to the recent extended wavelength scale for CIE dominant wavelength. Many effects are newly reported.