Bregman vantage point trees for efficient nearest Neighbor Queries

Nearest neighbor (NN) retrieval is a crucial tool of many computer vision tasks. Since the brute-force naive search is too time consuming for most applications, several tailored data structures have been proposed to improve the efficiency of NN search. Among these, vantage point tree (vp-tree) was introduced for information retrieval in metric spaces. Vptrees have recently shown very good performances for image patch retrieval with respect to the L₂ metric. In this paper we generalize the seminal vp-tree construction and search algorithms to the broader class of Bregman divergences. These distorsion measures are preferred in many cases, as they also handle entropic distances (e.g., Kullback-Leibler divergence) besides quadratic distances. We also extend vp-tree to deal with symmetrized Bregman divergences, which are commonplace in applications of content-based multimedia retrieval. We evaluated performances of our Bvp-tree for exact and approximate NN search on two image feature datasets. Our results show good performances of Bvp-tree, specially for symmetrized Bregman NN queries.