This is a reimprementation of the approximate nearest neighbor method (named Backet Distance Hashing; BDH) persented in International Conference on Computer Vision (ICCV) 2013. This is slightly faster than the original implementation.
Reference: Masakazu Iwamura, Tomokazu Sato and Koichi Kise "What Is the Most Efficient Way to Select Nearest Neighbor Candidates for Fast Approximate Nearest Neighbor Search?" http://www.m.cs.osakafu-u.ac.jp/cgi-bin/publication_public.cgi?func=show_detail&id=1357