1. A method of determining correspondence between image regions, the method comprising: identifying first and second regions of visual content including pixels in a computer system, the first region comprising a first patch of pixels having a first mapping to a second patch of pixels in the second region; performing iterative evaluations of the first and second regions, each iterative evaluation including at least (i) a first evaluation phase selecting a best mapping for the first patch, according to a distance metric, the best mapping selected from among the first mapping and a second mapping obtained from mappings of nearby pixels, and (ii) a second evaluation phase selecting one of the best mapping and a third mapping obtained by perturbing the second mapping; and recording a result of the iterative evaluations in the computer system that indicates a third patch of pixels in the second region identified in the iterative evaluations.