IWP: Token Pruning as Implicit Weight Pruning in Large Vision Language Models

Dong-Jae Lee, Sunghyun Baek, Junmo Kim


Abstract
Large Vision–Language Models (LVLMs) show impressive performance across image and video understanding tasks, yet their computational cost grows rapidly with the number of visual tokens. Existing token pruning methods address this by reducing the number of visual tokens, but overlook the internal mechanism of attention. In this paper, we propose a novel training-free token pruning framework grounded in the dual-form perspective of attention. We reformulate attention as an implicit linear layer whose weight matrix is the sum of rank-1 outer products, each generated by a single token’s key–value pair. Token pruning thus reduces to identifying an optimal subset of these rank-1 updates that retains the essential information of the original dual weight matrix. Extending this perspective to standard softmax attention in LVLMs, we derive a novel importance metric quantifying both a token’s information magnitude and information duplication. To efficiently select the subset with the proposed metric, we introduce Progressive Chunked Maximal Marginal Relevance. Extensive experiments demonstrate that our method achieves a better trade-off between performance and efficiency, while providing another perspective on existing pruning approaches.
Anthology ID:
2026.findings-emnlp.1778
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
38025–38047
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.1778/
DOI:
Bibkey:
Cite (ACL):
Dong-Jae Lee, Sunghyun Baek, and Junmo Kim. 2026. IWP: Token Pruning as Implicit Weight Pruning in Large Vision Language Models. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 38025–38047, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
IWP: Token Pruning as Implicit Weight Pruning in Large Vision Language Models (Lee et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.1778.pdf