Global-Local Interplay in Semantic Alignment for Few-Shot Learning

Few-shot learning aims to recognize novel classes from only a few labeled training examples. Aligning semantically relevant local regions has shown promise in effectively comparing a query image with support images. However, global information is usually overlooked in the existing approaches, resulting in a higher possibility of learning semantics unrelated to the global information. To address this issue, we propose a Global-Local Interplay Metric Learning (GLIML) framework to employ the interplay between global features and local features to guide semantic alignment. We first design a Global-Local Information Concurrent Learning (GLICL) module to extract both global features and local features and perform global-local interplay. We then design a Global-Local Information Cross-Covariance Estimator (GLICCE) to learn the similarity on the global-local interplay, in contrast to the current practice where only local features are considered. Visualizations show that the global-local interplay decreases (1) the weights placed on the semantics that are irrelevant to the global information and (2) the variability of the learned features within every class in the feature space. Quantitative experiments on three benchmark datasets demonstrate that GLIML achieves state-of-the-art performance while maintaining high efficiency.