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Leveraging Out-of-Distribution Unlabeled Images: Semi-Supervised Semantic Segmentation with an Open-Vocabulary Model

4 Jul 2025archive 2025-07-28

WooSeok Shin, Jisu Kang, Hyeonki Jeong, Jin Sob Kim, Sung Won Han

In semi-supervised semantic segmentation, existing studies have shown promising results in academic settings with controlled splits of benchmark datasets. However, the potential benefits of leveraging significantly larger sets of unlabeled images remain unexplored. In real-world scenarios, abundant unlabeled images are often available from online sources (web-scraped images) or large-scale datasets. However, these images may have different distributions from those of the target dataset, a situation known as out-of-distribution (OOD). Using these images as unlabeled data in semi-supervised learning can lead to inaccurate pseudo-labels, potentially misguiding network training. In this paper, we propose a new semi-supervised semantic segmentation framework with an open-vocabulary segmentation model (SemiOVS) to effectively utilize unlabeled OOD images. Extensive experiments on Pascal VOC and Context datasets demonstrate two key findings: (1) using additional unlabeled images improves the performance of semi-supervised learners in scenarios with few labels, and (2) using the open-vocabulary segmentation (OVS) model to pseudo-label OOD images leads to substantial performance gains. In particular, SemiOVS outperforms existing PrevMatch and SemiVL methods by +3.5 and +3.0 mIoU, respectively, on Pascal VOC with a 92-label setting, achieving state-of-the-art performance. These findings demonstrate that our approach effectively utilizes abundant unlabeled OOD images for semantic segmentation tasks. We hope this work can inspire future research and real-world applications. The code is available at https://github.com/wooseok-shin/SemiOVS

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wooseok-shin/SemiOVS mentioned in paperpytorch report

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Tasks

Pseudo LabelSegmentationSemantic SegmentationSemi-Supervised Semantic Segmentation

Results from the paper archive 2025-07-28

TaskDatasetModelMetricValueRank at snapshotLeaderboardReport
Semi-Supervised Semantic Segmentation PASCAL VOC 2012 1464 labels SemiOVS (w/ SemiVL, ViT-B/16) Validation mIoU 88.0 #2 of 17 Archive leaderboard report
Semi-Supervised Semantic Segmentation PASCAL VOC 2012 1464 labels SemiOVS (w/ UniMatch, ResNet-101) Validation mIoU 81.8 #7 of 17 Archive leaderboard report
Semi-Supervised Semantic Segmentation PASCAL VOC 2012 183 labeled SemiOVS (w/ SemiVL, ViT-B/16) Validation mIoU 87.3 #2 of 16 Archive leaderboard report
Semi-Supervised Semantic Segmentation PASCAL VOC 2012 183 labeled SemiOVS (w/ UniMatch, ResNet-101) Validation mIoU 81.3 #4 of 16 Archive leaderboard report
Semi-Supervised Semantic Segmentation PASCAL VOC 2012 183 labeled SemiOVS (w/ UniMatch, ResNet-50) Validation mIoU 78.7 #6 of 16 Archive leaderboard report
Semi-Supervised Semantic Segmentation PASCAL VOC 2012 25% labeled SemiOVS (w/ PrevMatch, ResNet-101) Validation mIoU 81.3 #1 of 27 Archive leaderboard report
Semi-Supervised Semantic Segmentation PASCAL VOC 2012 25% labeled SemiOVS (w/ UniMatch, ResNet-101) Validation mIoU 81.0 #3 of 27 Archive leaderboard report
Semi-Supervised Semantic Segmentation PASCAL VOC 2012 366 labeled SemiOVS (w/ SemiVL, ViT-B/16) Validation mIoU 87.5 #2 of 15 Archive leaderboard report
Semi-Supervised Semantic Segmentation PASCAL VOC 2012 366 labeled SemiOVS (w/ UniMatch, ResNet-101) Validation mIoU 81.6 #5 of 15 Archive leaderboard report
Semi-Supervised Semantic Segmentation PASCAL VOC 2012 732 labeled SemiOVS (w/ SemiVL, ViT-B/16) Validation mIoU 87.9 #2 of 16 Archive leaderboard report
Semi-Supervised Semantic Segmentation PASCAL VOC 2012 732 labeled SemiOVS (w/ UniMatch, ResNet-101) Validation mIoU 81.7 #5 of 16 Archive leaderboard report
Semi-Supervised Semantic Segmentation PASCAL VOC 2012 92 labeled SemiOVS (w/ SemiVL, ViT-B/16) Validation mIoU 87.0 #1 of 17 Archive leaderboard report
Semi-Supervised Semantic Segmentation PASCAL VOC 2012 92 labeled SemiOVS (w/ UniMatch, ResNet-101) Validation mIoU 80.4 #4 of 17 Archive leaderboard report
Semi-Supervised Semantic Segmentation PASCAL VOC 2012 92 labeled SemiOVS (w/ UniMatch, ResNet-50) Validation mIoU 78.2 #5 of 17 Archive leaderboard report
Semi-Supervised Semantic Segmentation Pascal VOC 2012 12.5% labeled SemiOVS (w/ UniMatch, ResNet-101) Validation mIoU 82.4 #1 of 38 Archive leaderboard report
Semi-Supervised Semantic Segmentation Pascal VOC 2012 12.5% labeled SemiOVS (w/ PrevMatch, ResNet-101) Validation mIoU 82.3 #2 of 38 Archive leaderboard report
Semi-Supervised Semantic Segmentation Pascal VOC 2012 6.25% labeled SemiOVS (w/ PrevMatch, ResNet-101) Validation mIoU 82.0 #1 of 19 Archive leaderboard report
Semi-Supervised Semantic Segmentation Pascal VOC 2012 6.25% labeled SemiOVS (w/ UniMatch, ResNet-101) Validation mIoU 81.5 #3 of 19 Archive leaderboard report

Ranks are positions in the archive's leaderboards as they stood at the 2025-07-28 snapshot. Results published since then are not among these rows, so a rank here is not a current standing.

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