FLOSS: Free Lunch in Open-vocabulary Semantic Segmentation

Fuente: arXiv
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Autores principales: Benigmim, Yasser, Fahes, Mohammad, Vu, Tuan-Hung, Bursuc, Andrei, de Charette, Raoul
Formato: Preprint
Publicado: 2025
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author Benigmim, Yasser
Fahes, Mohammad
Vu, Tuan-Hung
Bursuc, Andrei
de Charette, Raoul
author_facet Benigmim, Yasser
Fahes, Mohammad
Vu, Tuan-Hung
Bursuc, Andrei
de Charette, Raoul
contents In this paper, we challenge the conventional practice in Open-Vocabulary Semantic Segmentation (OVSS) of using averaged class-wise text embeddings, which are typically obtained by encoding each class name with multiple templates (e.g., a photo of <class>, a sketch of a <class>). We investigate the impact of templates for OVSS, and find that for each class, there exist single-template classifiers--which we refer to as class-experts--that significantly outperform the conventional averaged classifier. First, to identify these class-experts, we introduce a novel approach that estimates them without any labeled data or training. By leveraging the class-wise prediction entropy of single-template classifiers, we select those yielding the lowest entropy as the most reliable class-experts. Second, we combine the outputs of class-experts in a new fusion process. Our plug-and-play method, coined FLOSS, is orthogonal and complementary to existing OVSS methods, offering an improvement without the need for additional labels or training. Extensive experiments show that FLOSS consistently enhances state-of-the-art OVSS models, generalizes well across datasets with different distribution shifts, and delivers substantial improvements in low-data scenarios where only a few unlabeled images are available. Our code is available at https://github.com/yasserben/FLOSS .
format Preprint
id arxiv_https___arxiv_org_abs_2504_10487
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle FLOSS: Free Lunch in Open-vocabulary Semantic Segmentation
Benigmim, Yasser
Fahes, Mohammad
Vu, Tuan-Hung
Bursuc, Andrei
de Charette, Raoul
Computer Vision and Pattern Recognition
Machine Learning
In this paper, we challenge the conventional practice in Open-Vocabulary Semantic Segmentation (OVSS) of using averaged class-wise text embeddings, which are typically obtained by encoding each class name with multiple templates (e.g., a photo of <class>, a sketch of a <class>). We investigate the impact of templates for OVSS, and find that for each class, there exist single-template classifiers--which we refer to as class-experts--that significantly outperform the conventional averaged classifier. First, to identify these class-experts, we introduce a novel approach that estimates them without any labeled data or training. By leveraging the class-wise prediction entropy of single-template classifiers, we select those yielding the lowest entropy as the most reliable class-experts. Second, we combine the outputs of class-experts in a new fusion process. Our plug-and-play method, coined FLOSS, is orthogonal and complementary to existing OVSS methods, offering an improvement without the need for additional labels or training. Extensive experiments show that FLOSS consistently enhances state-of-the-art OVSS models, generalizes well across datasets with different distribution shifts, and delivers substantial improvements in low-data scenarios where only a few unlabeled images are available. Our code is available at https://github.com/yasserben/FLOSS .
title FLOSS: Free Lunch in Open-vocabulary Semantic Segmentation
topic Computer Vision and Pattern Recognition
Machine Learning
url https://arxiv.org/abs/2504.10487