EntropyPrune: Matrix Entropy Guided Visual Token Pruning for Multimodal Large Language Models

Fuente: arXiv
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Main Authors: Wang, Yahong, Wu, Juncheng, Ni, Zhangkai, Yang, Chengmei, Liu, Yihang, Yang, Longzhen, Zhou, Yuyin, Wen, Ying, He, Lianghua
Format: Preprint
Published: 2026
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author Wang, Yahong
Wu, Juncheng
Ni, Zhangkai
Yang, Chengmei
Liu, Yihang
Yang, Longzhen
Zhou, Yuyin
Wen, Ying
He, Lianghua
author_facet Wang, Yahong
Wu, Juncheng
Ni, Zhangkai
Yang, Chengmei
Liu, Yihang
Yang, Longzhen
Zhou, Yuyin
Wen, Ying
He, Lianghua
contents Multimodal large language models (MLLMs) incur substantial inference cost due to the processing of hundreds of visual tokens per image. Although token pruning has proven effective for accelerating inference, determining when and where to prune remains largely heuristic. Existing approaches typically rely on static, empirically selected layers, which limit interpretability and transferability across models. In this work, we introduce a matrix-entropy perspective and identify an "Entropy Collapse Layer" (ECL), where the information content of visual representations exhibits a sharp and consistent drop, which provides a principled criterion for selecting the pruning stage. Building on this observation, we propose EntropyPrune, a novel matrix-entropy-guided token pruning framework that quantifies the information value of individual visual tokens and prunes redundant ones without relying on attention maps. Moreover, to enable efficient computation, we exploit the spectral equivalence of dual Gram matrices, reducing the complexity of entropy computation and yielding up to a 64x theoretical speedup. Extensive experiments on diverse multimodal benchmarks demonstrate that EntropyPrune consistently outperforms state-of-the-art pruning methods in both accuracy and efficiency. On LLaVA-1.5-7B, our method achieves a 68.2% reduction in FLOPs while preserving 96.0% of the original performance. Furthermore, EntropyPrune generalizes effectively to high-resolution and video-based models, highlighting the strong robustness and scalability in practical MLLM acceleration. The code will be publicly available at https://github.com/YahongWang1/EntropyPrune.
format Preprint
id arxiv_https___arxiv_org_abs_2602_17196
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle EntropyPrune: Matrix Entropy Guided Visual Token Pruning for Multimodal Large Language Models
Wang, Yahong
Wu, Juncheng
Ni, Zhangkai
Yang, Chengmei
Liu, Yihang
Yang, Longzhen
Zhou, Yuyin
Wen, Ying
He, Lianghua
Computer Vision and Pattern Recognition
Multimodal large language models (MLLMs) incur substantial inference cost due to the processing of hundreds of visual tokens per image. Although token pruning has proven effective for accelerating inference, determining when and where to prune remains largely heuristic. Existing approaches typically rely on static, empirically selected layers, which limit interpretability and transferability across models. In this work, we introduce a matrix-entropy perspective and identify an "Entropy Collapse Layer" (ECL), where the information content of visual representations exhibits a sharp and consistent drop, which provides a principled criterion for selecting the pruning stage. Building on this observation, we propose EntropyPrune, a novel matrix-entropy-guided token pruning framework that quantifies the information value of individual visual tokens and prunes redundant ones without relying on attention maps. Moreover, to enable efficient computation, we exploit the spectral equivalence of dual Gram matrices, reducing the complexity of entropy computation and yielding up to a 64x theoretical speedup. Extensive experiments on diverse multimodal benchmarks demonstrate that EntropyPrune consistently outperforms state-of-the-art pruning methods in both accuracy and efficiency. On LLaVA-1.5-7B, our method achieves a 68.2% reduction in FLOPs while preserving 96.0% of the original performance. Furthermore, EntropyPrune generalizes effectively to high-resolution and video-based models, highlighting the strong robustness and scalability in practical MLLM acceleration. The code will be publicly available at https://github.com/YahongWang1/EntropyPrune.
title EntropyPrune: Matrix Entropy Guided Visual Token Pruning for Multimodal Large Language Models
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2602.17196