DIRECT ESTIMATION OF LIGHTNESS OF SURFACE COLORS

Experiments were made to determine whether the lightness of color surfaces is related to luminous reflectance by a power function and whether, for a given dominant wavelength, lightness varies as a function of the colorimetric purity. Experiments are reported on an array of 104 reflecting surfaces, scaled by the method of magnitude estimation. Data are given on rates of growth of lightness of blue, green, yellow, and red samples, and of the inverse attribute darkness, with lightness and darkness of a gray surface seen under artificial light and in natural daylight.