ICE: Inter-Instance Contrastive Encoding for Unsupervised Person Re-Identification

Hao Chen, Benoit Lagadec, Francois Bremond; Proceedings of the IEEE/CVF International Conference on Computer Vision (ICCV), 2021, pp. 14960-14969

Abstract


Unsupervised person re-identification (ReID) aims at learning discriminative identity features without annotations. Recently, self-supervised contrastive learning has gained increasing attention for its effectiveness in unsupervised representation learning. The main idea of instance contrastive learning is to match a same instance in different augmented views. However, the relationship between different instances has not been fully explored in previous contrastive methods, especially for instance-level contrastive loss. To address this issue, we propose Inter-instance Contrastive Encoding (ICE) that leverages inter-instance pairwise similarity scores to boost previous class-level contrastive ReID methods. We first use pairwise similarity ranking as one-hot hard pseudo labels for hard instance contrast, which aims at reducing intra-class variance. Then, we use similarity scores as soft pseudo labels to enhance the consistency between augmented and original views, which makes our model more robust to augmentation perturbations. Experiments on several large-scale person ReID datasets validate the effectiveness of our proposed unsupervised method ICE, which is competitive with even supervised methods. Code is made available at https://github.com/chenhao2345/ICE.

Related Material


[pdf] [supp] [arXiv]
[bibtex]
@InProceedings{Chen_2021_ICCV, author = {Chen, Hao and Lagadec, Benoit and Bremond, Francois}, title = {ICE: Inter-Instance Contrastive Encoding for Unsupervised Person Re-Identification}, booktitle = {Proceedings of the IEEE/CVF International Conference on Computer Vision (ICCV)}, month = {October}, year = {2021}, pages = {14960-14969} }