Training-Free Class Purification for Open-Vocabulary Semantic Segmentation

Fuente: arXiv
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Main Authors: Chen, Qi, Yang, Lingxiao, Chen, Yun, Zhao, Nailong, Lai, Jianhuang, Shao, Jie, Xie, Xiaohua
Format: Preprint
Published: 2025
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author Chen, Qi
Yang, Lingxiao
Chen, Yun
Zhao, Nailong
Lai, Jianhuang
Shao, Jie
Xie, Xiaohua
author_facet Chen, Qi
Yang, Lingxiao
Chen, Yun
Zhao, Nailong
Lai, Jianhuang
Shao, Jie
Xie, Xiaohua
contents Fine-tuning pre-trained vision-language models has emerged as a powerful approach for enhancing open-vocabulary semantic segmentation (OVSS). However, the substantial computational and resource demands associated with training on large datasets have prompted interest in training-free methods for OVSS. Existing training-free approaches primarily focus on modifying model architectures and generating prototypes to improve segmentation performance. However, they often neglect the challenges posed by class redundancy, where multiple categories are not present in the current test image, and visual-language ambiguity, where semantic similarities among categories create confusion in class activation. These issues can lead to suboptimal class activation maps and affinity-refined activation maps. Motivated by these observations, we propose FreeCP, a novel training-free class purification framework designed to address these challenges. FreeCP focuses on purifying semantic categories and rectifying errors caused by redundancy and ambiguity. The purified class representations are then leveraged to produce final segmentation predictions. We conduct extensive experiments across eight benchmarks to validate FreeCP's effectiveness. Results demonstrate that FreeCP, as a plug-and-play module, significantly boosts segmentation performance when combined with other OVSS methods.
format Preprint
id arxiv_https___arxiv_org_abs_2508_00557
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Training-Free Class Purification for Open-Vocabulary Semantic Segmentation
Chen, Qi
Yang, Lingxiao
Chen, Yun
Zhao, Nailong
Lai, Jianhuang
Shao, Jie
Xie, Xiaohua
Computer Vision and Pattern Recognition
Fine-tuning pre-trained vision-language models has emerged as a powerful approach for enhancing open-vocabulary semantic segmentation (OVSS). However, the substantial computational and resource demands associated with training on large datasets have prompted interest in training-free methods for OVSS. Existing training-free approaches primarily focus on modifying model architectures and generating prototypes to improve segmentation performance. However, they often neglect the challenges posed by class redundancy, where multiple categories are not present in the current test image, and visual-language ambiguity, where semantic similarities among categories create confusion in class activation. These issues can lead to suboptimal class activation maps and affinity-refined activation maps. Motivated by these observations, we propose FreeCP, a novel training-free class purification framework designed to address these challenges. FreeCP focuses on purifying semantic categories and rectifying errors caused by redundancy and ambiguity. The purified class representations are then leveraged to produce final segmentation predictions. We conduct extensive experiments across eight benchmarks to validate FreeCP's effectiveness. Results demonstrate that FreeCP, as a plug-and-play module, significantly boosts segmentation performance when combined with other OVSS methods.
title Training-Free Class Purification for Open-Vocabulary Semantic Segmentation
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2508.00557