2017 年 53 巻 5 号 p. 178-185
Visibility is a psychological quantity based on the physical properties of media such as printed papers or electronic display devices. An objective assessment standard of visibility has not yet been established. To construct an objective assessment standard, photometric equipment has been developed. The present paper proposes a quantitative model of visibility for two different observational distances. One is 3 meters for signage, and the other is 0.5 meters for reading. As a result, contrast (Lcon), space frequency (Cpd) and luminance coefficient (ρ) were selected as independent variables in the model of visibility for 3 meters. On the other hand, contrast (Lcon) and space frequency (Cpd) were selected in the model of visibility for 0.5 meters. Consequently, the effects of ‘Lcon’ decreased and ‘Cpd’ increased when the observational distance is changed from 3 meters to 0.5 meters. Furthermore, the physical feature of target for directing visual attention seems to change depending on the observational distance.
