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Mar 19, 2020


The implementation of Self-supervised Equivariant Attention Mechanism for Weakly Supervised Semantic Segmentaion.

You can also download the repository from


Image-level weakly supervised semantic segmentation is a challenging problem that has been deeply studied in recentyears. Most of advanced solutions exploit class activation map (CAM). However, CAMs can hardly serve as the object mask due to the gap between full and weak supervisions. In this paper, we propose a self-supervised equivariant attention mechanism (SEAM) to discover additional supervision and narrow the gap. Our method is based on the observation that equivariance is an implicit constraint in fully supervised semantic segmentation, whose pixel-level labels take the same spatial transformation as the input images during data augmentation. However, this constraint is lost on the CAMs trained by image-level supervision. Therefore, we propose consistency regularization on predicted CAMs from various transformed images to provide self-supervision for network learning. Moreover, we propose a pixel correlation module (PCM), which exploits context appearance information and refines the prediction of current pixel by its similar neighbors, leading to further improvement on CAMs consistency. Extensive experiments on PASCAL VOC 2012 dataset demonstrate our method outperforms state-of-the-art methods using the same level of supervision.

Thanks to the work of jiwoon-ahn, the code of this repository borrow heavly from his AffinityNet repository, and we follw the same pipeline to verify the effectiveness of our SEAM.


  • Python 3.6
  • pytorch 0.4.1, torchvision 0.2.1
  • CUDA 9.0
  • 4 x GPUs (12GB)



  • Download the repository.
git clone
  • Install python dependencies.
pip install -r requirements.txt
ln -s $your_dataset_path/VOCdevkit/VOC2012 VOC2012
  • (Optional) The image-level labels have already been given in voc12/cls_label.npy. If you want to regenerate it (which is unnecessary), please download the annotation of VOC 2012 SegmentationClassAug training set (containing 10582 images), which can be download here and place them all as VOC2012/SegmentationClassAug/xxxxxx.png. Then run the code
cd voc12
python --voc12_root VOC2012

SEAM step

  1. SEAM training
python --voc12_root VOC2012 --weights $pretrained_model --session_name $your_session_name
  1. SEAM inference.
python --weights $SEAM_weights --infer_list [voc12/val.txt | voc12/train.txt | voc12/train_aug.txt] --out_cam $your_cam_dir --out_crf $your_crf_dir
  1. SEAM step evaluation. We provide python mIoU evaluation script, or you can use official development kit. Here we suggest to show the curve of mIoU with different background score.
python --list VOC2012/ImageSets/Segmentation/[val.txt | train.txt] --predict_dir $your_cam_dir --gt_dir VOC2012/SegmentationClass --comment $your_comments --type npy --curve True

Random walk step

The random walk step keep the same with AffinityNet repository.

  1. Train AffinityNet.
python --weights $pretrained_model --voc12_root VOC2012 --la_crf_dir $your_crf_dir_4.0 --ha_crf_dir $your_crf_dir_24.0 --session_name $your_session_name
  1. Random walk propagation
python --weights $aff_weights --infer_list [voc12/val.txt | voc12/train.txt] --cam_dir $your_cam_dir --voc12_root VOC2012 --out_rw $your_rw_dir
  1. Random walk step evaluation
python --list VOC2012/ImageSets/Segmentation/[val.txt | train.txt] --predict_dir $your_rw_dir --gt_dir VOC2012/SegmentationClass --comment $your_comments --type png

Pseudo labels retrain

Pseudo label retrain on DeepLabv1. Code is available here.


Please cite our paper if the code is helpful to your research.

    author = {Yude Wang and Jie Zhang and Meina Kan and Shiguang Shan and Xilin Chen},
    title = {Self-supervised Equivariant Attention Mechanism for Weakly Supervised Semantic Segmentation},
    booktitle = {Proc. IEEE Conference on Computer Vision and Pattern Recognition (CVPR)},
    year = {2020}


[1] J. Ahn and S. Kwak. Learning pixel-level semantic affinity with image-level supervision for weakly supervised semantic segmentation. In Proc. IEEE Conference on Computer Vision and Pattern Recognition (CVPR), 2018.


Self-supervised Equivariant Attention Mechanism for Weakly Supervised Semantic Segmentation, CVPR 2020 (Oral)




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