1. A computer-readable storage medium storing thereon processor-executable instructions that when executed perform actions, the actions comprising: obtaining one or more feature descriptors; determining a similarity score for each feature descriptor with respect to a captured image, the similarity score representing a closest match of a feature descriptor to an image patch in the captured image, the similarity score computed for those feature descriptors matching an image patch in the captured image, the matching feature descriptors determined by a min-hash process; and recognizing the captured image through use of the similarity scores.