A ratio model of perceptual transparency

A ratio model of the achromatic transparency of a phenomenal surface on a b ipartite background is proposed. The model asserts that transparency corres ponds to the evaluation of the ratio of the lightness difference inside the transparent surface to the difference in reference lightness inside the ba ckground. It applies to both balanced and unbalanced transparency. The rati o model was compared experimentally with the previous perceptual model of a chromatic transparency proposed by Metelli. Each model was tested by compar ing the rated with the predicted transparency. Analysis shows that the rati o model provides better predictions of transparency than those provided by Metelli's model.