1994 Volume 50 Issue 4 Pages 511-517
During radiographic imaging, it is very important that the results of physical evaluation correspond with that of the subjective evaluation. However the gradient curve, MTF and Wiener spectrum as physical indices do not correspondence to results of subjective evaluation. Utlizing the minimum perceptble density difference (ΔDmin), the human psychological effect is introduced into conventional psysical data. Our psychophysical data, by using ΔDmin, represent human eyes response to brightness, color tones and physical information quantity of screen/film systems. So the values of psychophysical data are in good agreement with the human vision sense when we observe X-ray films illuminated by viewing box. Therefore, it is very important when observing, we should include characteristics of human vision and the viewing box into its physical quantity.
