1. A method of image analysis, comprising: (a) receiving, by a computer system, image data including at least first and second descriptors describing portions of the image data; (b) processing, by the computer system, the image data to generate at least one conditional probability of observing the first descriptor in the image data given an occurrence of the second descriptor so as to coordinate the first and second descriptors; and (c) training, by the computer system, at least one classifier based on the conditional probability.