Sine-Wave Response of the Visual System I The Mach Phenomenon*

Abstract

In order to develop a complete specification for the appraisal of the quality of a photographic system by the use of sine-wave response functions, the sine-wave response of the complete visual system must also be known. A method has been worked out for determining the above-mentioned response of the eye. Whenever the eye views a diffuse luminous boundary in which a sudden change of luminance gradient occurs, a bright line appears at the junction of the gradient and the higher luminance, and a dark line at the junction of the gradient and the lower luminance. This phenomenon is a purely subjective one, because physical measurements of the luminances involved show no luminance higher or lower than the two between which the gradient exists.