Brightness of Clothes at Various Illuminance Levels

Abstract

Brightness of 16 different clothes was investigated under various illumination levels covering 1000 to 0.01 lx. A gray scale made of 15 steps of lightness was used to evaluate the brightness. Red clothes lost their brightness gradually as the illuminance level decreased, while the most of the blue ones slightly gained their brightness when the level became extremely low. A blue cl oth of very small brightness, however, lost its brightness for less illuminance on the contrary to the commonly accepted phenomenon of the Purkinje shift. A yellow cloth did not show any change in its brightness. These characteristics of brightness change did not depend on the materials, but only on the colors of clothes. The starting point of mesopic vision was estimated from the present results as about 3 lx.