Experimental Verification of Optimum Density Obtained from Psychophysical Gradients

Abstract

The optimum density is the density at which the best detectability is attained. The theoretical optimum density was obtained using psychophysical gradients (psychophysically modified gradients). The experimental optimum densities obtained by a visual experiment were compared with the theoretical optimum densities for radiographs of three types of object: two periodic fabrics having spatial frequencies oft and 3 mm^-1 and a step-edge fabric using two kinds of film. The experimental optimum densities coincided in all cases with the theoretical optimum densities at which psychophysical gradient values reached maxima. The psychophysical gradient ivas confirmed to be useful for obtaining the optimum density.