A PSYCHOPHYSICAL AND COMPUTATIONAL ANALYSIS OF INTENSITY-BASED STEREO

We describe two psychophysical experiments testing predictions of the square difference mechanism we have previously proposed for intensity- based stereo. Experiment 1 assesses the relative contributions of disp arity and contrast to intensity-based stereo by measuring detection th resholds. The product of disparity and contrast at threshold is shown to be constant. In experiment 2, we measure quantitatively the global depth position perceived in stereograms of curved, smoothly shaded sur faces. The results show that disparity averaging over the surface invo lves a contrast-dependent weighting function. The results from both ex periments are consistent with predictions derived from the square diff erence mechanism. The relation of this mechanism to feature correspond ence stereopsis and shape-from-shading is discussed and a general fram ework for assessing the modularity of stereopsis is presented.