抄録
Although a number of studies have been reported on the distribution of the B/L ratio in the chromaticity diagram, most of the results were measured with a simple achromatic surround condition. In real life we encounter a variety of visual environments that contain many colors of different luminance. Thus we measured the distribution of the B/L ratio in the chromaticity diagram under five different surround conditions: one was a dark condition comparable with those in previous studies, and the others were pictures of real scenes such as daytime residential, daytime downtown, nighttime downtown, and nighttime residential areas. The results obtained under the nighttime residential surround showed good agreement with the results of the dark surround, whereas the results of the other three surround conditions showed some deviations from the dark surround results. The average deviation of the B/L ratio from the dark surround results increased as a function of the average luminance of the surround. This suggests that the average luminance of the scenery surround is an important factor in determining the B/L ratio.
