Impressions of Overall Brightness in a Non-Uniformly Illuminated Space

摘要

References(7) When an interior space is illuminated non-uniformly, we perceive different levels of brightness. The strongly illuminated areas give a bright impression while the weakly illuminated areas give dark impression. In other words, the whole space is divided into several portions which have different levels of brightness. The purpose of this study is to estimate overall impression of brightness which is divided into such portions which have different brightness. Two experiments were carried out in this research to assess brightness of whole spaces those were illuminated non-uniformly. In the first experiment, luminance distribution images of an interior space were used as stimuli. In the second experiment, actual interior spaces of non-uniform lighting were used as stimuli. From these results, it could be concluded that the whole space that is illuminated non-uniformly is perceived darker than the space illuminated uniformly. The overall impression of brightness of the space that is illuminated non-uniformly could not explained on the basis of the quantitative average of the luminances. It could be corresponded with the psychological average of all portions’ brightness those were divided by the illumination level.