Implement Referring Expression Comprehension by Extending Auto-focus Lens to Locked Vision Model

Referring Expression Comprehension (REC) aims to achieve fine-grained cross-modal content alignment. The traditional two-stage approaches, by decomposing REC into localization (region proposal) and comprehension (expression-based ranking), lead to the isolation of continuous image information and heavily rely on the quality of the proposals. In this paper, we propose a point-based two-stage framework for REC to quickly achieve localization by inserting a language-modulated auto-focus module into the locked vision model. Specifically, we redefine REC as two processes: point-based cross-modal comprehension and point-based instance localization. For the comprehension stage, we reconstruct the raw annotations into soft masks at the feature point level as a metric of cross-modal correlation. With this indirect metric, REC can be approximated as a binary classification problem, which fundamentally avoids the impact of isolated regions. Remarkably, soft masks are shape-independent, which means our method is extremely general. By switching different vision models, different types of predictions ( e.g. , localization and segmentation) can be obtained. Experiments on multiple benchmarks demonstrate the feasibility and potential of our point-based paradigm. Our code will be public at https://github.com/VILAN-Lab/PBREC-AF .