Edge co-occurrences can account for rapid categorization of natural versus animal images- Supplementary Material

A method for measuring the statistics of edge co-occurrences in natural images was demonstrated by Geisler, Perry, Super & Gallogly [21]. Here we extend their method in two important ways. First, we use an over-complete, multi-scale representation of edges, which is more similar to the output of the primary visual cortex. Second, we use a synthesis model for the edge representation, so that the edges we detect are guaranteed to be sufficient to regenerate the image with a low error. Here we describe each of these procedures (see SI Figure 1), along with the construction of the statistics of edge co-occurrences (see Section 1.3) and the implementation of the classifier (see Section 1.4).