Not All Pixels are Equal: Learning Pixel Hardness for Semantic Segmentation.

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Title: Not All Pixels are Equal: Learning Pixel Hardness for Semantic Segmentation.
Authors: Xiao, Xin1 (AUTHOR) xinxiao@whu.edu.cn, Zhou, Daiguo2 (AUTHOR) zhoudaiguo@xiaomi.com, Hu, Jiagao2 (AUTHOR) hujiagao@xiaomi.com, Hu, Yi3 (AUTHOR) huyi@whmit.cn, Xu, Yongchao1 (AUTHOR) yongchao.xu@whu.edu.cn
Source: International Journal of Computer Vision. Jul2025, Vol. 133 Issue 7, p4669-4689. 21p.
Subjects: Direct costing, Source code, Values (Ethics), Hardness, Whistles
Abstract: Semantic segmentation has witnessed great progress. Despite the impressive overall results, the segmentation performance in some hard areas (e.g., small objects or thin parts) is still not promising. A straightforward solution is hard sample mining. Yet, most existing hard pixel mining strategies for semantic segmentation often rely on pixel's loss value, which tends to decrease during training. Intuitively, the pixel hardness for segmentation mainly depends on image structure and is expected to be stable. In this paper, we propose to learn pixel hardness for semantic segmentation by leveraging hardness information contained in global and historical loss values. More precisely, we add a gradient-independent branch for learning a hardness level (HL) map by maximizing hardness-weighted segmentation loss, which is minimized for the segmentation head. This encourages large hardness values in difficult areas, leading to appropriate and stable HL map. Despite its simplicity, the proposed method can be applied to most segmentation methods with no and marginal extra cost during inference and training, respectively. Without bells and whistles, the proposed method achieves consistent improvement (1.37% mIoU on average) over most popular semantic segmentation methods on the Cityscapes dataset, and demonstrates good generalization ability across domains. The source codes are available at this link. [ABSTRACT FROM AUTHOR]
Copyright of International Journal of Computer Vision is the property of Springer Nature and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
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  Data: Not All Pixels are Equal: Learning Pixel Hardness for Semantic Segmentation.
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  Data: <searchLink fieldCode="JN" term="%22International+Journal+of+Computer+Vision%22">International Journal of Computer Vision</searchLink>. Jul2025, Vol. 133 Issue 7, p4669-4689. 21p.
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  Data: Semantic segmentation has witnessed great progress. Despite the impressive overall results, the segmentation performance in some hard areas (e.g., small objects or thin parts) is still not promising. A straightforward solution is hard sample mining. Yet, most existing hard pixel mining strategies for semantic segmentation often rely on pixel's loss value, which tends to decrease during training. Intuitively, the pixel hardness for segmentation mainly depends on image structure and is expected to be stable. In this paper, we propose to learn pixel hardness for semantic segmentation by leveraging hardness information contained in global and historical loss values. More precisely, we add a gradient-independent branch for learning a hardness level (HL) map by maximizing hardness-weighted segmentation loss, which is minimized for the segmentation head. This encourages large hardness values in difficult areas, leading to appropriate and stable HL map. Despite its simplicity, the proposed method can be applied to most segmentation methods with no and marginal extra cost during inference and training, respectively. Without bells and whistles, the proposed method achieves consistent improvement (1.37% mIoU on average) over most popular semantic segmentation methods on the Cityscapes dataset, and demonstrates good generalization ability across domains. The source codes are available at this link. [ABSTRACT FROM AUTHOR]
– Name: AbstractSuppliedCopyright
  Label:
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  Data: <i>Copyright of International Journal of Computer Vision is the property of Springer Nature and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.)
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RecordInfo BibRecord:
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        Value: 10.1007/s11263-025-02416-4
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      – Code: eng
        Text: English
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      – SubjectFull: Direct costing
        Type: general
      – SubjectFull: Source code
        Type: general
      – SubjectFull: Values (Ethics)
        Type: general
      – SubjectFull: Hardness
        Type: general
      – SubjectFull: Whistles
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      – TitleFull: Not All Pixels are Equal: Learning Pixel Hardness for Semantic Segmentation.
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          Name:
            NameFull: Xiao, Xin
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            NameFull: Zhou, Daiguo
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            NameFull: Hu, Jiagao
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            NameFull: Hu, Yi
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            NameFull: Xu, Yongchao
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            – D: 01
              M: 07
              Text: Jul2025
              Type: published
              Y: 2025
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