Efficient Interpretation Policies

Abstract

Many imaging systems seek a good interpretation of the scene presented --- i.e., a plausible (perhaps optimal) mapping from aspects of the scene to real-world objects. This paper addresses the issue of finding such likely mappings efficiently. In general, an "(interpretation) policy" specifies when to apply which "imaging operators", which can range from low-level edge-detectors and region-growers through highlevel token-combination--rules and expectation-driven objectdetectors. Given the costs of these operators and the distribution of possible images, we can determine both the expected cost and expected accuracy of any such policy. Our task is to find a maximally effective policy --- typically one with sufficient accuracy, whose cost is minimal. We explore this framework in several contexts, including the eigenface approach to face recognition. Our results show, in particular, that policies which select the operators that maximize information gain per unit cost work more effectively than other policies, including ones that, at each stage, simply try to establish the putative most-likely interpretation. Keywords: vision, decision theory, real time systems 1