Multi-Proxy Learning from an Entropy Optimization Perspective

Deep Metric Learning, a task that learns a feature embedding space where semantically similar samples are located closer than dissimilar samples, is a cornerstone of many computer vision applications. Most of the existing proxy-based approaches usually exploit the global context via learning a single proxy for each training class, which struggles in capturing the complex non-uniform data distribution with different patterns. In this work, we present an easy-to-implement framework to effectively capture the local neighbor relationships via learning multiple proxies for each class that collectively approximate the intra-class distribution. In the context of large intra-class visual diversity, we revisit the entropy learning under the multi-proxy learning framework and provide a training routine that both minimizes the entropy of intra-class probability distribution and maximizes the entropy of inter-class probability distribution. In this way, our model is able to better capture the intra-class variations and smooth the inter-class differences and thus facilitates to extract more semantic feature representations for the downstream tasks. Extensive experimental results demonstrate that the proposed approach achieves competitive performances. Codes and an appendix are provided.