An Embarrassingly Simple Approach to Discrete Supervised Hashing

Prior hashing works typically learn a projection function from high-dimensional visual feature space to low-dimensional latent space. However, such a projection function remains several crucial bottlenecks: 1) information loss and coding redundancy are inevitable; 2) the available information of semantic labels is not well-explored; 3) the learned latent embedding lacks explicit semantic meaning. To overcome these limitations, we propose a novel supervised Discrete Auto-Encoder Hashing (DAEH) framework, in which a linear auto-encoder can effectively project the semantic labels of images into a latent representation space. Instead of using the visual feature projection, the proposed DAEH framework skillfully explores the semantic information of supervised labels to refine the latent feature embedding and further optimizes hashing function. Meanwhile, we reformulate the objective and relax the discrete constraints for the binary optimization problem. Extensive experiments on Caltech-256, CIFAR-10, and MNIST datasets demonstrate that our method can outperform the state-of-the-art hashing baselines.