Normalizing Batch Normalization for Long-Tailed Recognition

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Hauptverfasser: Bao, Yuxiang, Kang, Guoliang, Yang, Linlin, Duan, Xiaoyue, Zhao, Bo, Zhang, Baochang
Format: Preprint
Veröffentlicht: 2025
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author Bao, Yuxiang
Kang, Guoliang
Yang, Linlin
Duan, Xiaoyue
Zhao, Bo
Zhang, Baochang
author_facet Bao, Yuxiang
Kang, Guoliang
Yang, Linlin
Duan, Xiaoyue
Zhao, Bo
Zhang, Baochang
contents In real-world scenarios, the number of training samples across classes usually subjects to a long-tailed distribution. The conventionally trained network may achieve unexpected inferior performance on the rare class compared to the frequent class. Most previous works attempt to rectify the network bias from the data-level or from the classifier-level. Differently, in this paper, we identify that the bias towards the frequent class may be encoded into features, i.e., the rare-specific features which play a key role in discriminating the rare class are much weaker than the frequent-specific features. Based on such an observation, we introduce a simple yet effective approach, normalizing the parameters of Batch Normalization (BN) layer to explicitly rectify the feature bias. To achieve this end, we represent the Weight/Bias parameters of a BN layer as a vector, normalize it into a unit one and multiply the unit vector by a scalar learnable parameter. Through decoupling the direction and magnitude of parameters in BN layer to learn, the Weight/Bias exhibits a more balanced distribution and thus the strength of features becomes more even. Extensive experiments on various long-tailed recognition benchmarks (i.e., CIFAR-10/100-LT, ImageNet-LT and iNaturalist 2018) show that our method outperforms previous state-of-the-arts remarkably. The code and checkpoints are available at https://github.com/yuxiangbao/NBN.
format Preprint
id arxiv_https___arxiv_org_abs_2501_03122
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Normalizing Batch Normalization for Long-Tailed Recognition
Bao, Yuxiang
Kang, Guoliang
Yang, Linlin
Duan, Xiaoyue
Zhao, Bo
Zhang, Baochang
Computer Vision and Pattern Recognition
In real-world scenarios, the number of training samples across classes usually subjects to a long-tailed distribution. The conventionally trained network may achieve unexpected inferior performance on the rare class compared to the frequent class. Most previous works attempt to rectify the network bias from the data-level or from the classifier-level. Differently, in this paper, we identify that the bias towards the frequent class may be encoded into features, i.e., the rare-specific features which play a key role in discriminating the rare class are much weaker than the frequent-specific features. Based on such an observation, we introduce a simple yet effective approach, normalizing the parameters of Batch Normalization (BN) layer to explicitly rectify the feature bias. To achieve this end, we represent the Weight/Bias parameters of a BN layer as a vector, normalize it into a unit one and multiply the unit vector by a scalar learnable parameter. Through decoupling the direction and magnitude of parameters in BN layer to learn, the Weight/Bias exhibits a more balanced distribution and thus the strength of features becomes more even. Extensive experiments on various long-tailed recognition benchmarks (i.e., CIFAR-10/100-LT, ImageNet-LT and iNaturalist 2018) show that our method outperforms previous state-of-the-arts remarkably. The code and checkpoints are available at https://github.com/yuxiangbao/NBN.
title Normalizing Batch Normalization for Long-Tailed Recognition
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2501.03122