Abstract
Owing to the effect of light scattering in the eyeball, the actual luminance of the image on the retina is not the same as the nominal luminance of the viewing object. The inconsistency in present visibility analysis is originated in this fact.
The actual luminance at the fovea is defined as effective luminance, and by introducing this effective luminance into visibility problems, the visibility analysis can be constructed on a single principle, and the estimation method of visivility can be rationalized and simplified.
The basis of this study is the uni-dimensional effective luminance function F(θ), which represents the effective luminance distribution perpendicular to the borderline of the two planes having luminances 1 and 0cm/d2. The effective luminance for any visual target can be decided from F(θ), and the equi-visual-acuity charts can be known from it.
Authers suggest that the many pending problems on visibility, such as adaptation luminance for non-uniform visual field, dynamic evaluation of visibility, bluring of the shape of the image on the retina, all can be understood clearly by use of the effective luminance conception.
