Learning to Rematch Mismatched Pairs for Robust Cross-Modal Retrieval
Authors: Haochen Han, Qinghua Zheng, Guang Dai, Minnan Luo, Jingdong Wang

Collecting well-matched multimedia datasets is crucial for training cross-modal retrieval models. However in real-world scenarios massive multimodal data are harvested from the Internet which inevitably contains Partially Mismatched Pairs (PMPs). Undoubtedly such semantical irrelevant data will remarkably harm the cross-modal retrieval performance. Previous efforts tend to mitigate this problem by estimating a soft correspondence to down-weight the contribution of PMPs. In this paper we aim to address this challenge from a new perspective: the potential semantic similarity among unpaired samples makes it possible to excavate useful knowledge from mismatched pairs. To achieve this we propose L2RM a general framework based on Optimal Transport (OT) that learns to rematch mismatched pairs. In detail L2RM aims to generate refined alignments by seeking a minimal-cost transport plan across different modalities. To formalize the rematching idea in OT first we propose a self-supervised cost function that automatically learns from explicit similarity-cost mapping relation. Second we present to model a partial OT problem while restricting the transport among false positives to further boost refined alignments. Extensive experiments on three benchmarks demonstrate our L2RM significantly improves the robustness against PMPs for existing models. The code is available at https://github.com/hhc1997/L2RM.