Assessment of color search performance in photopic and mesopic illuminances based on color identification data

Abstract

Color is an effective attribute as an aid to a visual task. Appearance of colors, however, remarkably changes with viewing conditions. In particular, lighting environment has strong effects on the appearance of surface colors. To use colors effectively, we must know how colors are identified under various lighting conditions. In our previous studies, we obtained the data on identification of colors under illuminances from photopic to mesopic levels. In this study we examined performance of a color related searching task under photopic and mesopic illuminance levels, and evaluated it based on the color identification data. Subjects searched the target three-digits printed on a card from among 45 cards. At the same time, a color chip was pasted on each plate as a clue. Before each trial the subjects were informed of the number and color name for the target on that trial. If the subjects could identify colors properly,.the searching performance must be improved. As might be expected, the performance of the task declined with decreasing illuminances and size of the color chip. It was found that the searching performance correlated with probability of being identified as the target color.