Optimal Transport for Label-Efficient Visible-Infrared Person Re-Identification

Visible-infrared person re-identification (VI-ReID) has been a key enabler for night intelligent monitoring system. However, the extensive laboring efforts significantly limit its applications. In this paper, we raise a new label-efficient training pipeline for VI-ReID. Our observation is: RGB ReID datasets have rich annotation information and annotating infrared images is expensive due to the lack of color information. In our approach, it includes two key steps: 1) We utilize the standard unsupervised domain adaptation technique to generate the pseudo labels for visible subset with the help of well-annotated RGB datasets; 2) We propose an optimal-transport strategy trying to assign pseudo labels from visible to infrared modality. In our framework, each infrared sample owns a label assignment choice, and each pseudo label requires unallocated images. By introducing uniform sample-wise and label-wise prior, we achieve a desirable assignment plan that allows us to find matched visible and infrared samples, and thereby facilitates cross-modality learning. Besides, a prediction alignment loss is designed to eliminate the negative effects brought by the incorrect pseudo labels. Extensive experimental results on benchmarks demonstrate the effectiveness of our approach. Code will be released at https://github.com/wjm-wjm/OTLA-ReID.