Chromatic adaptation to illumination investigated with adapting and adapted color

Abstract

The state of chromatic adaptation was investigated by using the two‐room technique. This technique involves a subject in a room who looks a white board in a separate test room through a window and judges the color of the window using the elementary color naming method. When the subject room is illuminated with a colored light and the test room with a white light, the window appears to be a very vivid color, for which the apparent hue depends on the color of the subject room. The color is referred to as the adapted color. The subject also evaluated the appearance of the illumination color of the subject room, which is called the adapting color. Two types of illuminating light in the subject room, fluorescent lamps with 7 colors and LED lamps with 19 colors, were employed. The adapting and the adapted colors were plotted on a polar diagram that was used in the opponent color theory, from which the hue angles were obtained. The hue angle difference between the two colors did not appear to be 180° except for one pair of adapting and the adapted colors, which implies that chromatic adaptation does not follow the opponent color concept. An improvement was achieved to explain the results by introducing complementary colors relation between the adapting and adapted color.

Color appearance of afterimages compared to the chromatic adaptation to illumination

“…The curve of Δθ does not follow the 180° line, implying that the adapting and afterimage colors do not obey the opponent colors relation. This finding is similar to that obtained by the two‐room technique, where the adaptation was to illumination of LED and fluorescent light . In Figure , the present results are plotted together with the previous results by filled and open symbols, respectively.…”

“…If a subject observes a white board placed at the position of the display through a window W while the subject room is illuminated by a colored light, which was called the adapting color, the subject perceives a vivid color at the window filled with the white board, which was called the adapted color. The relationship between the adapting and the adapted colors were investigated in a previous article . The luminance on the front wall varied from 17 to 60 cd/m 2 depending on the color of the subject room.…”

“…A state of chromatic adaptation can be shown by the color of a psychophysically achromatic patch under illumination by various colors, which was realized by the two‐room technique . A subject room is illuminated by a colored light, and a person observes a psychophysically achromatic board placed in a test room illuminated by a white light through a window opened at the separating wall of the two rooms.…”

Chromatic adaptation in a 2D photograph demonstrated by a D‐up viewer

“…The most interesting result is the amount of chromaticness observed at the window W. It was shown by the 2‐room technique that in a real space, the color of the window appears very vivid, with the subject room illuminated by a colored light, which is not realized in the simultaneous color contrast experiment. Therefore, we expected that the color of the window will also and should appear very vivid with the D‐up viewing condition similar to the real space condition.…”

“…On the wall separating the 2 rooms, a small window W with a size of 3 × 3 cm 2 (1.56° × 1.56° of the visual angle) was opened, and through the window, a subject could observe a test stimulus T of the achromatic board of N6 placed in the test room. When the illuminating light in the subject room was colored, the achromatic board T or the window W appeared in a vivid color that was roughly opposite to the illumination color, indicating chromatic adaptation to the illumination . The distance from the subject to the window W was 110 cm.…”