1. A system configured for generating a probabilistic similarity measure based on a first intensity value and a second intensity value of a digital image, the system comprising: a computing device; a noise characterization module configured for determining noise characteristics of a camera producing the digital image and configured for forming a noise curve descriptive of the noise characteristics; a comparison module configured for calculating a probability of correspondence, based at least in part on the noise curve, for each possible true intensity value of a set of possible true intensity values wherein each of the probabilities of correspondence indicate similarity between the first intensity value and the second intensity value relative to the corresponding possible true intensity value; and an integration module implemented at least in part by the computing device and configured for performing an integration of the probabilities of correspondence resulting in a probabilistic similarity measure that is a probability that the first intensity value and the second intensity value correspond to the same intensity value.