UFineBench: Towards Text-based Person Retrieval with Ultra-fine Granularity
Authors: Jialong Zuo, Hanyu Zhou, Ying Nie, Feng Zhang, Tianyu Guo, Nong Sang, Yunhe Wang, Changxin Gao

Existing text-based person retrieval datasets often have relatively coarse-grained text annotations. This hinders the model to comprehend the fine-grained semantics of query texts in real scenarios. To address this problem we contribute a new benchmark named UFineBench for text-based person retrieval with ultra-fine granularity. Firstly we construct a new dataset named UFine6926. We collect a large number of person images and manually annotate each image with two detailed textual descriptions averaging 80.8 words each. The average word count is three to four times that of the previous datasets. In addition of standard in-domain evaluation we also propose a special evaluation paradigm more representative of real scenarios. It contains a new evaluation set with cross domains cross textual granularity and cross textual styles named UFine3C and a new evaluation metric for accurately measuring retrieval ability named mean Similarity Distribution (mSD). Moreover we propose CFAM a more efficient algorithm especially designed for text-based person retrieval with ultra fine-grained texts. It achieves fine granularity mining by adopting a shared cross-modal granularity decoder and hard negative match mechanism. With standard in-domain evaluation CFAM establishes competitive performance across various datasets especially on our ultra fine-grained UFine6926. Furthermore by evaluating on UFine3C we demonstrate that training on our UFine6926 significantly improves generalization to real scenarios compared with other coarse-grained datasets. The dataset and code will be made publicly available at https://github.com/Zplusdragon/UFineBench.