Space brightness evaluated using border luminance of color appearance mode

Abstract

In previous study, we defined the border luminance as space brightness and investigated what determines border luminance in a real environment. We undertook a second study to confirm that perceived brightness of a room is determined solely by border luminance. We also examined the correlation between change in the magnitude of space brightness and change in the border luminance. To investigate these two points, we measured space brightness using three methods: magnitude estimation, space-brightness matching, and border-luminance adjustment. We found that, the border luminance is the same even though the illuminance of the room or the configuration of interior surface reflectance is different, the matched illuminance is the same. The brightness value obtained using the magnitude estimation method was proportional to the 0.56th power of the border luminance. Our results clearly show that space brightness can be evaluated quantitatively using border luminance adjustment even if the brightness cannot be measured using the horizontal illuminance. Therefore, measuring the border luminance is an effective way to supplement existing photometric systems.