Ordinal Characteristics of Transparency

Edward H. Adelson and P. Anandan

Published in
AAAI-90 Workshop on Qualitative Vision (pp. 77-81)
Boston, MA; July 29 (1990)
Transparency can arise in images due to a number of different physical phenomena. We have proposed a pre-physical level of representation in which a number primitive images organized as layers combine together to form an observed image. The ordinal relationships between the luminances at an X junction can be used categorize the X junction as non-, single-, and double-reversing junctions. These categories can be determined without precise measurements, and are robust against point nonlinearities in luminance sensitivity. Non- and single-reversing junctions support transparency; single-reversing junctions lead to an unambiguous interpretation of depth-order of the layers, while non-reversing junctions leave the depth-order ambiguous. Double-reversing junctions do not support transparency. Propogation of these constraints can be used to rapidly restrict the set of the legal interpretations of an image.