Abstract
It is a research of the impression of soft light judged seeing the shadow. Three facts became clear by the experiment. 1.The impression of soft light is not caused when the shadow is not perceivable. 2.The reflectivity of the plane of incidence of light doesn't control the impression. And, the evaluation is decided by guessing the entering quantities of light. 3.The shape of the object that makes the shadow doesn't influence the impression.
Based on the above result, it looked for the physical value in which it was able to explain the level of soft light. Then, the illuminance change ratio and the impression in the part that was the shadow of the object had the correlation. In this report, the illumination distribution calculated at intervals of 1mm was requested, and the value in which the difference between an arbitrary point and eight adjoining points is averaged is named S. Light with soft maximum value of S is an impression and correlates.
