1. A method comprising: partitioning a plurality of images of an image space into a plurality of coarse clusters, the partitioning based at least in part on signatures of the plurality of images determined from compact descriptors of the plurality of images; creating a refined cluster that includes one or more images of an individual coarse cluster based at least in part on pair-wise comparisons of the compact descriptors, from which the signatures are determined, of images of the individual coarse cluster; identifying the refined cluster as a set of duplicate images; and searching another coarse cluster of images for ones of the other coarse cluster to add to the refined cluster based at least in part on an average of the compact descriptors of the images of the refined cluster.