StructSAM: Structure- and Spectrum-Preserving Token Merging for Segment Anything Models

Fuente: arXiv
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Auteurs principaux: Nguyen, Duy M. H., Tran, Tuan A., Nguyen, Duong, Xie, Siwei, Nguyen, Trung Q., Truong, Mai T. N., Palenicek, Daniel, Le, An T., Barz, Michael, Nguyen, TrungTin, Dam, Tuan, Le, Ngan, Vu, Minh, Doan, Khoa, Ngo, Vien, Xie, Pengtao, Zou, James, Sonntag, Daniel, Peters, Jan, Niepert, Mathias
Format: Preprint
Publié: 2026
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author Nguyen, Duy M. H.
Tran, Tuan A.
Nguyen, Duong
Xie, Siwei
Nguyen, Trung Q.
Truong, Mai T. N.
Palenicek, Daniel
Le, An T.
Barz, Michael
Nguyen, TrungTin
Dam, Tuan
Le, Ngan
Vu, Minh
Doan, Khoa
Ngo, Vien
Xie, Pengtao
Zou, James
Sonntag, Daniel
Peters, Jan
Niepert, Mathias
author_facet Nguyen, Duy M. H.
Tran, Tuan A.
Nguyen, Duong
Xie, Siwei
Nguyen, Trung Q.
Truong, Mai T. N.
Palenicek, Daniel
Le, An T.
Barz, Michael
Nguyen, TrungTin
Dam, Tuan
Le, Ngan
Vu, Minh
Doan, Khoa
Ngo, Vien
Xie, Pengtao
Zou, James
Sonntag, Daniel
Peters, Jan
Niepert, Mathias
contents Recent token merging techniques for Vision Transformers (ViTs) provide substantial speedups by reducing the number of tokens processed by self-attention, often without retraining. However, their direct application to the Segment Anything Model (SAM) family is nontrivial: SAM's image encoder mixes windowed and global attention, and its mask decoder relies on dense, prompt-conditioned features for precise boundary prediction. We systematically evaluate representative token-merging methods on SAM and Medical SAM in a strict off-the-shelf setting, and find that existing destination-selection heuristics can erode boundaries and leak prompt information as merge rates increase. We propose \textbf{StructSAM}, a resolution-preserving merge-unmerge framework tailored to SAM. StructSAM computes a lightweight token-energy score from first-order feature gradients, uses grid-based flatness screening to protect boundary and prompt regions, and merges tokens within flat areas toward low-energy destinations with explicit token recovery. We further provide a spectral graph coarsening view showing that score-guided merging yields bounded Laplacian spectral distortion compared to random or window-restricted baselines. Across eight natural and medical benchmarks, StructSAM reduces encoder FLOPs by 25-30\% (up to 40\%+ with prompt-aware merging) with minor drops in mIoU/Dice, consistently outperforming ToMe, PiToMe, ToMeSD, VidToMe, and ALGM at the same compute.
format Preprint
id arxiv_https___arxiv_org_abs_2603_07307
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle StructSAM: Structure- and Spectrum-Preserving Token Merging for Segment Anything Models
Nguyen, Duy M. H.
Tran, Tuan A.
Nguyen, Duong
Xie, Siwei
Nguyen, Trung Q.
Truong, Mai T. N.
Palenicek, Daniel
Le, An T.
Barz, Michael
Nguyen, TrungTin
Dam, Tuan
Le, Ngan
Vu, Minh
Doan, Khoa
Ngo, Vien
Xie, Pengtao
Zou, James
Sonntag, Daniel
Peters, Jan
Niepert, Mathias
Computer Vision and Pattern Recognition
Machine Learning
Recent token merging techniques for Vision Transformers (ViTs) provide substantial speedups by reducing the number of tokens processed by self-attention, often without retraining. However, their direct application to the Segment Anything Model (SAM) family is nontrivial: SAM's image encoder mixes windowed and global attention, and its mask decoder relies on dense, prompt-conditioned features for precise boundary prediction. We systematically evaluate representative token-merging methods on SAM and Medical SAM in a strict off-the-shelf setting, and find that existing destination-selection heuristics can erode boundaries and leak prompt information as merge rates increase. We propose \textbf{StructSAM}, a resolution-preserving merge-unmerge framework tailored to SAM. StructSAM computes a lightweight token-energy score from first-order feature gradients, uses grid-based flatness screening to protect boundary and prompt regions, and merges tokens within flat areas toward low-energy destinations with explicit token recovery. We further provide a spectral graph coarsening view showing that score-guided merging yields bounded Laplacian spectral distortion compared to random or window-restricted baselines. Across eight natural and medical benchmarks, StructSAM reduces encoder FLOPs by 25-30\% (up to 40\%+ with prompt-aware merging) with minor drops in mIoU/Dice, consistently outperforming ToMe, PiToMe, ToMeSD, VidToMe, and ALGM at the same compute.
title StructSAM: Structure- and Spectrum-Preserving Token Merging for Segment Anything Models
topic Computer Vision and Pattern Recognition
Machine Learning
url https://arxiv.org/abs/2603.07307