LIGHTING DESIGN METHOD APPLICABLE BOTH TO DAY LIGHTING AND TO ELECTRIC LIGHTING USING LUMINANCE IMAGE

In order to promote energy-saving lighting, daylight should be utilized to the utmost extent in daytime and electric light should be added at minimum to the area where light is really insufficient. To realize such lighting design, it is required to estimate our adaptation level. One possible way to do so is to use luminance image in lighting design. The authors conducted experiments to find objective way to evaluate 'just sufficient light condition (JSLC)' based on luminance image and found it could be possible if we used a brightness image converted from a luminance image. Specifically JSLC to paper work and monitor work could be judged from the brightness value on the paper/monitor and the brightness value of the background. Furthermore JSLC to room appearance could also estimated by using area sizes of certain brightness values in the brightness image.