AU-LLM: Micro-Expression Action Unit Detection via Enhanced LLM-Based Feature Fusion

Fuente: arXiv
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Autores principales: Liu, Zhishu, Yuan, Kaishen, Zhao, Bo, Xu, Yong, Yu, Zitong
Formato: Preprint
Publicado: 2025
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author Liu, Zhishu
Yuan, Kaishen
Zhao, Bo
Xu, Yong
Yu, Zitong
author_facet Liu, Zhishu
Yuan, Kaishen
Zhao, Bo
Xu, Yong
Yu, Zitong
contents The detection of micro-expression Action Units (AUs) is a formidable challenge in affective computing, pivotal for decoding subtle, involuntary human emotions. While Large Language Models (LLMs) demonstrate profound reasoning abilities, their application to the fine-grained, low-intensity domain of micro-expression AU detection remains unexplored. This paper pioneers this direction by introducing \textbf{AU-LLM}, a novel framework that for the first time uses LLM to detect AUs in micro-expression datasets with subtle intensities and the scarcity of data. We specifically address the critical vision-language semantic gap, the \textbf{Enhanced Fusion Projector (EFP)}. The EFP employs a Multi-Layer Perceptron (MLP) to intelligently fuse mid-level (local texture) and high-level (global semantics) visual features from a specialized 3D-CNN backbone into a single, information-dense token. This compact representation effectively empowers the LLM to perform nuanced reasoning over subtle facial muscle movements.Through extensive evaluations on the benchmark CASME II and SAMM datasets, including stringent Leave-One-Subject-Out (LOSO) and cross-domain protocols, AU-LLM establishes a new state-of-the-art, validating the significant potential and robustness of LLM-based reasoning for micro-expression analysis. The codes are available at https://github.com/ZS-liu-JLU/AU-LLMs.
format Preprint
id arxiv_https___arxiv_org_abs_2507_21778
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle AU-LLM: Micro-Expression Action Unit Detection via Enhanced LLM-Based Feature Fusion
Liu, Zhishu
Yuan, Kaishen
Zhao, Bo
Xu, Yong
Yu, Zitong
Computer Vision and Pattern Recognition
The detection of micro-expression Action Units (AUs) is a formidable challenge in affective computing, pivotal for decoding subtle, involuntary human emotions. While Large Language Models (LLMs) demonstrate profound reasoning abilities, their application to the fine-grained, low-intensity domain of micro-expression AU detection remains unexplored. This paper pioneers this direction by introducing \textbf{AU-LLM}, a novel framework that for the first time uses LLM to detect AUs in micro-expression datasets with subtle intensities and the scarcity of data. We specifically address the critical vision-language semantic gap, the \textbf{Enhanced Fusion Projector (EFP)}. The EFP employs a Multi-Layer Perceptron (MLP) to intelligently fuse mid-level (local texture) and high-level (global semantics) visual features from a specialized 3D-CNN backbone into a single, information-dense token. This compact representation effectively empowers the LLM to perform nuanced reasoning over subtle facial muscle movements.Through extensive evaluations on the benchmark CASME II and SAMM datasets, including stringent Leave-One-Subject-Out (LOSO) and cross-domain protocols, AU-LLM establishes a new state-of-the-art, validating the significant potential and robustness of LLM-based reasoning for micro-expression analysis. The codes are available at https://github.com/ZS-liu-JLU/AU-LLMs.
title AU-LLM: Micro-Expression Action Unit Detection via Enhanced LLM-Based Feature Fusion
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2507.21778