1. A method comprising: under control of one or more processors of a computing device: receiving a search query; determining an initial set of ranked images associated with the search query; determining a degree of visual content similarity for each image of the initial set of ranked images with respect to one or more other images of the initial set of ranked images; selecting one or more confident image samples from the initial set of ranked images based at least in part on the degrees of visual content similarity; and reranking the initial set of ranked images using the one or more confident image samples.