ExpAlign: Expectation-Guided Vision-Language Alignment for Open-Vocabulary Grounding

Fuente: arXiv
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Autores principales: Hu, Junyi, Bai, Tian, Wu, Fengyi, Li, Wenyan, Peng, Zhenming, Zhang, Yi
Formato: Preprint
Publicado: 2026
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author Hu, Junyi
Bai, Tian
Wu, Fengyi
Li, Wenyan
Peng, Zhenming
Zhang, Yi
author_facet Hu, Junyi
Bai, Tian
Wu, Fengyi
Li, Wenyan
Peng, Zhenming
Zhang, Yi
contents Open-vocabulary grounding requires accurate vision-language alignment under weak supervision, yet existing methods either rely on global sentence embeddings that lack fine-grained expressiveness or introduce token-level alignment with explicit supervision or heavy cross-attention designs. We propose ExpAlign, a theoretically grounded vision-language alignment framework built on a principled multiple instance learning formulation. ExpAlign introduces an Expectation Alignment Head that performs attention-based soft MIL pooling over token-region similarities, enabling implicit token and instance selection without additional annotations. To further stabilize alignment learning, we develop an energy-based multi-scale consistency regularization scheme, including a Top-K multi-positive contrastive objective and a Geometry-Aware Consistency Objective derived from a Lagrangian-constrained free-energy minimization. Extensive experiments show that ExpAlign consistently improves open-vocabulary detection and zero-shot instance segmentation, particularly on long-tail categories. Most notably, it achieves 36.2 AP$_r$ on the LVIS minival split, outperforming other state-of-the-art methods at comparable model scale, while remaining lightweight and inference-efficient.
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id arxiv_https___arxiv_org_abs_2601_22666
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publishDate 2026
record_format arxiv
spellingShingle ExpAlign: Expectation-Guided Vision-Language Alignment for Open-Vocabulary Grounding
Hu, Junyi
Bai, Tian
Wu, Fengyi
Li, Wenyan
Peng, Zhenming
Zhang, Yi
Computer Vision and Pattern Recognition
Open-vocabulary grounding requires accurate vision-language alignment under weak supervision, yet existing methods either rely on global sentence embeddings that lack fine-grained expressiveness or introduce token-level alignment with explicit supervision or heavy cross-attention designs. We propose ExpAlign, a theoretically grounded vision-language alignment framework built on a principled multiple instance learning formulation. ExpAlign introduces an Expectation Alignment Head that performs attention-based soft MIL pooling over token-region similarities, enabling implicit token and instance selection without additional annotations. To further stabilize alignment learning, we develop an energy-based multi-scale consistency regularization scheme, including a Top-K multi-positive contrastive objective and a Geometry-Aware Consistency Objective derived from a Lagrangian-constrained free-energy minimization. Extensive experiments show that ExpAlign consistently improves open-vocabulary detection and zero-shot instance segmentation, particularly on long-tail categories. Most notably, it achieves 36.2 AP$_r$ on the LVIS minival split, outperforming other state-of-the-art methods at comparable model scale, while remaining lightweight and inference-efficient.
title ExpAlign: Expectation-Guided Vision-Language Alignment for Open-Vocabulary Grounding
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2601.22666