  Hashing has been widely used for large-scale search due to its low storage
cost and fast query speed. By using supervised information, supervised hashing
can significantly outperform unsupervised hashing. Recently, discrete
supervised hashing and deep hashing are two representative progresses in
supervised hashing. On one hand, hashing is essentially a discrete optimization
problem. Hence, utilizing supervised information to directly guide discrete
(binary) coding procedure can avoid sub-optimal solution and improve the
accuracy. On the other hand, deep hashing, which integrates deep feature
learning and hash-code learning into an end-to-end architecture, can enhance
the feedback between feature learning and hash-code learning. The key in
discrete supervised hashing is to adopt supervised information to directly
guide the discrete coding procedure in hashing. The key in deep hashing is to
adopt the supervised information to directly guide the deep feature learning
procedure. However, there have not existed works which can use the supervised
information to directly guide both discrete coding procedure and deep feature
learning procedure in the same framework. In this paper, we propose a novel
deep hashing method, called deep discrete supervised hashing (DDSH), to address
this problem. DDSH is the first deep hashing method which can utilize
supervised information to directly guide both discrete coding procedure and
deep feature learning procedure, and thus enhance the feedback between these
two important procedures. Experiments on three real datasets show that DDSH can
outperform other state-of-the-art baselines, including both discrete hashing
and deep hashing baselines, for image retrieval.

Information Retrieval