Before revision:  We first identify a parametrized 66-dimensional space of grayscale textures defined by local spatial correlationsbetween discrete light intensities. We then devise a method of measuring the contribution of each of these textures to the spatial structure of scenes. Efficient coding predicts that the perceptual salienceof a complex sensory signal should be related to its variability in natural settings. Based on an analysis of contrast-equalized natural scenes, this theory predicts that textures involving two-point correlations will be most salient, and it further predicts the relative salienceamong second-order correlations of different types.
After revision:  We first identify a parametrized 66-dimensional space of local grayscale light-intensity correlations, and measure the relevance of each direction to natural scenes. The "variance is salience" hypothesis predicts that two-point correlations will be most salient, and it further predicts the relative salienceamong second-order correlations of different types.