抄録
This paper has described some of the applications of auther's apparent brightness scales to the contrast and the visual acuity. The summary is as follows ; 1. The definition of the contrast, which is widely used presently, has many irrationalities in both of the objective sense and the subjective sense. To clear away those irrationalities, "Apparent Contrast" was defined as a difference of apparent brightness between object and background at a given adaptation level. 2. When the apparent contrast is defined as above, the values of the apparent contrast for a certain visual acuity are reasonably constant at any adaptation levels above 50 asb. 3. The following informations were found out from the considerations about decreasing apparent contrast due to veiling luminance, a) The apparent contrast decreases with increasing the veiling luminance. b) Even though the value of veiling luminance is fixed, the apparent contrast is affected significantly when the luminance of object is higher, or the contrast is lower. c) A veiling luminance have a greater effect on the apparent contrast when the eye adaptation level is lower. b) and c) are the informations observed from the consideration of apparent brightness only. 4. An experiment on the decreasing visual acuity caused to the veiling was carried out, and it was comfirmed that the informations mentioned above do not contradict with the experimental results. 5. Discussions on the brightness constancy which appears to the brightness perception were made, and the property of the apparent brightness scales was deduced.
