REVIEW 3 major objections 5 minor 37 references
Compress Any Segment Anything Model (SAM)
T0 review · 3 major / 5 minor · reviewed 2026-08-06 · deepseek-v4-flash
Pith's one-line read The paper claims that any Segment Anything Model can be compressed to roughly a fifth of its size by storing each pair of weights as one integer index on a dense trajectory, with under 1% segmentation loss and no fine-tuning.
desk verdict Birkhoff is a legitimate extension of Hyper-Compression to SAMs with strong external results, but the 60-second and inference-acceleration claims are overstated and need fixing. read the letter →
The pith
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
The reading
What carries the argument
The carrying object is the dense torus trajectory generated by the fractional-part map $\tau(z)=z-\lfloor z\rfloor$ with frequency vector $a=[1/(\pi+1),1/(\pi+2)]$, or its adaptive variant $a=[(l/U),l]/\sqrt{(l/U)^2+l^2}$. Because $a_1,a_2$ are irrationally related, the set $\{\tau(\theta\cdot a):\theta\in\{0,\ldots,U\}\}$ samples a curve that is dense in the unit square, so each adjacent weight pair $w^{(g)}$ is encoded by the single integer $\theta^*_g$ that best reproduces it (Eqs. 7-15). Algorithm 1 searches over the box size $l$, codebook size $U$, and category count $M$ to minimize mean absolute error, and the HyperLinear operator fuses decompression with a block matrix product (Eq. 23) so that one memory access decodes two parameters during inference.
What would settle it
Run Birkhoff's Algorithm 1 on a SAM variant with outlier-heavy or strongly non-uniform linear-layer weights, for instance a model with weights far outside the chosen box before scaling, using the default hyperparameters of Table IV, and measure the mIoU change on SA-1B. If a mean absolute error near 0.002 is accompanied by a performance drop larger than 1%, the finite-codebook coverage assumption is falsified; similarly, finding any model in the 18-model family whose post-compression score drop exceeds 1% under the reported settings would contradict the core claim.
Extended reading notes
Core claim
The paper's central claim is that a SAM layer's weight matrix can be replaced by a much smaller integer matrix $\Theta$ plus a few auxiliary scalars, with no data and no retraining, because each $1\times 2$ block of adjacent weights is reproduced to within a small mean absolute error by evaluating a one-parameter fractional-part trajectory at an integer index. On 18 SAM-family models tested on COCO, LVIS, and SA-1B, the paper reports compression ratios above 4.3x for most models (5.17x for SAM2-B) and post-compression mIoU/mAP changes almost always inside 1%, with the whole compression finished in under 60 seconds for most models. The paper also claims that its fused HyperLinear operator keeps inference essentially at the original model's speed, and that on COCO box-prompt segmentation the data-free method matches or beats fine-tuning-based and data-free quantization baselines at comparable ratios.
Load-bearing premise
For every layer of every SAM variant, each pair of adjacent weights must be close enough to one of the finitely many sampled points on the trajectory that the integer-index approximation keeps the accumulated error beneath the level that changes segmentation scores by about 1%.
Editorial extensions
If this is right
- Compression without retraining sidesteps catastrophic forgetting and the need for the original training data, which is often unavailable for domain-specific SAM variants.
- At 4-5x compression, storage footprint drops from hundreds of megabytes or gigabytes to tens or hundreds of megabytes, making large ViT-H models more feasible on mobile and edge devices.
- Most models compress in under 60 seconds, so a cloud-based model factory could batch-compress many SAM variants on demand.
- Because HyperLinear fuses decompression with matrix multiplication, post-compression inference stays close to the original speed, with the largest models losing only a few percent of speed.
- On COCO box-prompt segmentation, the data-free Birkhoff result at 4-5x ratio matches or beats INT6 quantization baselines, even ones that use fine-tuning.
Reading between the lines
- Editorial extension: the mechanism is not SAM-specific; any network whose weights are stored as dense matrices could be compressed the same way, so the strongest untested implication is that the same fidelity guarantee may transfer to other transformer-heavy vision and language models.
- Editorial extension: the compression ratio is currently tied to the group size of two weights per integer index, so pushing substantially beyond 5x would require trajectories dense in higher dimensions, entropy coding of the stored indices, or a relaxation of the sub-1% performance budget.
- Editorial extension: the paper's link between MAE and downstream mIoU is empirical; a rigorous bound connecting codebook size $U$, MAE, and final segmentation accuracy would let a practitioner verify the 1% guarantee before deployment rather than after.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The paper proposes Birkhoff, a data-free compression method for Segment Anything Models and their variants. The method builds on Hyper-Compression, which replaces each pair of weights by a single integer index along a dense one-dimensional trajectory, and introduces a fused CUDA operator, HyperLinear, that combines decompression with matrix multiplication to preserve inference speed. The authors report experiments on 18 SAM variants across COCO, LVIS, and SA-1B, claiming compression ratios of 3.3x to 5.17x, compression times mostly under one minute, post-compression performance drops mostly within 1%, and inference slowdowns of only a few percent. The code is open-sourced.
Significance. If the empirical claims hold, Birkhoff is a practically valuable data-free alternative to quantization, pruning, and distillation for SAM-family models. The evaluation is broad (18 models, three external datasets) and uses external mIoU/mAP metrics, so the central results are not circularly validated. The open-sourced code, the absence of fine-tuning data requirements, and the dedicated HyperLinear operator for inference acceleration are concrete strengths. The main weaknesses are that the universal claims in the abstract and introduction are stronger than the reported measurements, and the finite-codebook approximation used in the actual algorithm lacks a supporting error bound.
major comments (3)
- [Abstract and Section I vs. Section IV-B1/Figure 6] The abstract states that 'the compression is finished within 60 seconds for all models' and the introduction repeats 'no more than 60s in all cases.' This is directly contradicted by Section IV-B1 and Figure 6, which report 95.33 seconds for SAM-H, 96.54 seconds for SAM-HQ-H, and 95.40 seconds for MobileSAMv2(ViT-H); the text itself acknowledges that these ViT-H models take 'approximately 90 seconds.' Since fast compression is a core advertised advantage of the method, this overclaim must be corrected by restating the bound as applying to most models or by reporting the ViT-H times as a separate class.
- [Section III-A, Eq. (8), and Algorithm 1] Equation (8) asserts that for every weight pair and every epsilon there exists a continuous theta* satisfying the approximation, but Algorithm 1 searches only over integers 0..U, with U chosen from a small candidate set per model. The paper provides no bound connecting U, the finite trajectory sampling spacing, per-layer reconstruction MAE, and downstream segmentation accuracy. This matters because a layer whose weights are not near the sampled trajectory could push the performance drop above the claimed 1%. Please supply either a worst-case MAE bound as a function of U or an empirical sensitivity analysis reporting per-layer reconstruction error, the worst-case layer, and mIoU/mAP degradation as U varies.
- [Section III-A, Figure 6, and Table IV] The compression ratio is not precisely defined. The method stores one integer per pair of float weights, which by itself yields at most a 4x ratio if the integer is stored as int16 and 8x if stored as uint8, yet the paper reports ratios of 4.31x to 5.17x. The manuscript must specify the bit-width and packing format of the stored integer tensor and auxiliary parameters, and state how the reported ratio is computed. This is also necessary for a fair comparison with the INT6 quantization ratios in Table VI.
minor comments (5)
- [Section IV-B1] The text says 'For instance, SAM-B achieves a 5.17x ratio in 20.83 seconds,' but Figure 6 reports 5.17x and 20.83 seconds for SAM2-B, while SAM-B has 4.31x and 15.81 seconds; this appears to be a typo and should be corrected so the headline example matches the abstract.
- [Throughout] There are several typos: 'cetegories' in Section III-A.2, 'ompress' in Section IV-B1, and 'Supplymentary' in Section IV-B2. These should be fixed.
- [Eq. (23)] The symbol S is used both for the scaling factor in the decompression formula and for the block size in Eqs. (17) and (22); please rename one of them to avoid ambiguity.
- [References] Reference [10] lists the arXiv identifier as '2023.09602', which does not appear to be valid; please verify and correct the identifier.
- [Section IV-B2] Detailed per-model results are deferred to a 'Supplementary' that is not included with the manuscript; please include at least one table in the main text with per-model mIoU/mAP before and after compression so that the 'within 1% in most cases' claim can be checked directly.
Circularity Check
No circularity: the compression method is re-derived in place, hyperparameters are fit by MAE in the usual lossy-compression sense, and the central claims are validated on external benchmarks; the 60-second timing overclaim is an internal accuracy error, not a circular derivation.
full rationale
Birkhoff's derivation chain is not circular. The Hyper-Compression mechanism is fully described in Sections II-C and III-A of this paper: pairs of weights are encoded by an irrational-rotation trajectory theta -> tau(theta*a), and the existence of a dense trajectory is supported by ergodic theory [31], an external mathematical source, rather than by the authors' own prior work. Although the method is inherited from the authors' own [13], the present paper re-derives the relevant equations (Eqs. 4-15) and Algorithm 1 in place; [13] functions as an attribution, not as the load-bearing justification for the compression guarantee. The hyperparameters (l, U, M) are selected by minimizing decompression MAE on the model's own weights (Algorithm 1, Section III-C1), which is ordinary rate-distortion fitting in lossy compression, and the paper does not rename this fit as a prediction. The claimed validation ('less than 1% drop', 'compression ratio 5.17x') is measured on held-out external benchmarks (COCO, LVIS, SA-1B) against the original models, so the central claim has independent empirical content. The abstract's 'compression is finished within 60 seconds for all models' is contradicted by the paper's own Figure 6, which reports 95.33s, 96.54s, and 95.40s for the three ViT-H models; this is a factual/consistency defect in the reported results, not a circularity of the derivation. No fitted parameter is relabeled as a prediction, no uniqueness claim is imported from the authors' prior work, and no ansatz is hidden behind a citation. Therefore no circular step is present.
Assumptions & free parameters
free parameters (3)
- l (box side length) =
0.1 for all models (chosen from alternatives)
- U (trajectory upper bound) =
per-model candidate sets, e.g., 1600 for SAM-B, up to 40000 for sensitive models
- M (number of scaling categories) =
[1,2,3] for all models
assumptions (4)
- standard math The sequence tau(theta*a) with a=[1/(pi+1), 1/(pi+2)] is dense in [0,1]^2 because a1 and a2 are irrationally independent (Sec III-A).
- domain assumption After centering and scaling into a box of side l, most or all weight pairs lie close enough to the discrete trajectory that the nearest of U+1 codebook points yields MAE around 0.001 (Eq. 8, Eq. 14, Figure 3).
- domain assumption Minimizing mean absolute error between original and decompressed weights is a sufficient proxy for preserving segmentation mIoU/mAP (Algorithm 1, Sec IV-A2).
- domain assumption The prior Hyper-Compression algorithm from [13] is correct and directly applicable to SAM linear layers (Sec II-C).
Cite this review
Pith. "Pith review of Compress Any Segment Anything Model (SAM)." pith.science (2026). https://pith.science/paper/G6WBBX2M
@misc{pith2026250708765,
author = {Pith},
title = {Pith review of: Compress Any Segment Anything Model (SAM)},
year = {2026},
howpublished = {\url{https://pith.science/paper/G6WBBX2M}},
note = {Machine review of arXiv:2507.08765}
}
read the original abstract
Due to the excellent performance in yielding high-quality, zero-shot segmentation, Segment Anything Model (SAM) and its variants have been widely applied in diverse scenarios such as healthcare and intelligent manufacturing. Therefore, effectively compressing SAMs has become an increasingly pressing practical need. In this study, we propose Birkhoff, a novel data-free compression algorithm for SAM and its variants. Unlike quantization, pruning, distillation, and other compression methods, Birkhoff embodies versatility across model types, agility in deployment, faithfulness to the original model, and compactness in model size. Specifically, Birkhoff introduces a novel compression algorithm: Hyper-Compression, whose core principle is to find a dense trajectory to turn a high-dimensional parameter vector into a low-dimensional scalar. Furthermore, Birkhoff designs a dedicated linear layer operator, HyperLinear, to fuse decompression and matrix multiplication to significantly accelerate inference of the compressed SAMs. Extensive experiments on 18 SAMs in the COCO, LVIS, and SA-1B datasets show that Birkhoff performs consistently and competitively in compression time, compression ratio, post-compression performance, and inference speed. For example, Birkhoff can achieve a compression ratio of 5.17x on SAM2-B, with less than 1% performance drop without using any fine-tuning data. Moreover, the compression is finished within 60 seconds for all models.
Figures
Figures from the paper (5 more)
Reference graph
Works this paper leans on
-
[1]
Segment anything,
A. Kirillov, E. Mintun, N. Ravi, H. Mao, C. Rolland, L. Gustafson, T. Xiao, S. Whitehead, A. C. Berg, W.-Y . Loet al., “Segment anything,” in Proceedings of the IEEE/CVF international conference on computer vision, 2023, pp. 4015–4026
2023
-
[2]
Medsam-u: Uncertainty-guided auto multi-prompt adaptation for reliable medsam,
N. Zhou, K. Zou, K. Ren, M. Luo, L. He, M. Wang, Y . Chen, Y . Zhang, H. Chen, and H. Fu, “Medsam-u: Uncertainty-guided auto multi-prompt adaptation for reliable medsam,”arXiv preprint arXiv:2409.00924, 2024
arXiv 2024
-
[3]
Segment anything in high quality,
L. Ke, M. Ye, M. Danelljan, Y .-W. Tai, C.-K. Tang, F. Yuet al., “Segment anything in high quality,” Advances in Neural Information Processing Systems, vol. 36, pp. 29 914–29 934, 2023
work page 2023
-
[4]
Mobilesamv2: Faster segment anything to everything,
C. Zhang, D. Han, S. Zheng, J. Choi, T.-H. Kim, and C. S. Hong, “Mobilesamv2: Faster segment anything to everything,” arXiv preprint arXiv:2312.09579, 2023
arXiv 2023
-
[5]
Sam 2: Segment anything in images and videos,
N. Ravi, V . Gabeur, Y .-T. Hu, R. Hu, C. Ryali, T. Ma, H. Khedr, R. R¨adle, C. Rolland, L. Gustafson et al., “Sam 2: Segment anything in images and videos,” arXiv preprint arXiv:2408.00714 , 2024
arXiv 2024
-
[6]
Edgesam: Prompt-in-the- loop distillation for on-device deployment of sam,
C. Zhou, X. Li, C. C. Loy, and B. Dai, “Edgesam: Prompt-in-the- loop distillation for on-device deployment of sam,” arXiv preprint arXiv:2312.06660, 2023
arXiv 2023
-
[7]
Efficientsam: Leveraged masked image pretraining for efficient segment anything,
Y . Xiong, B. Varadarajan, L. Wu, X. Xiang, F. Xiao, C. Zhu, X. Dai, D. Wang, F. Sun, F. Iandola et al. , “Efficientsam: Leveraged masked image pretraining for efficient segment anything,” in Proceedings of the IEEE/CVF Conference on Computer Vision and Pattern Recognition , 2024, pp. 16 111–16 121
work page 2024
-
[8]
Tinysam: Pushing the envelope for efficient segment anything model,
H. Shu, W. Li, Y . Tang, Y . Zhang, Y . Chen, H. Li, Y . Wang, and X. Chen, “Tinysam: Pushing the envelope for efficient segment anything model,” in Proceedings of the AAAI Conference on Artificial Intelligence, vol. 39, no. 19, 2025, pp. 20 470–20 478
work page 2025
Show all 37 references
-
[9]
Segment anything in medical images,
J. Ma, Y . He, F. Li, L. Han, C. You, and B. Wang, “Segment anything in medical images,” Nature Communications, vol. 15, no. 1, p. 654, 2024
2024
-
[10]
An empir- ical study of catastrophic forgetting in large language models during continual fine-tuning,
Y . Luo, Z. Yang, F. Meng, Y . Li, J. Zhou, and Y . Zhang, “An empir- ical study of catastrophic forgetting in large language models during continual fine-tuning,” arXiv preprint arXiv:2023.09602 , 2023
2023
-
[11]
A survey on model compression for large language models,
X. Zhu, J. Li, Y . Liu, C. Ma, and W. Wang, “A survey on model compression for large language models,” Transactions of the Association for Computational Linguistics , vol. 12, pp. 1556–1577, 2024
2024
-
[12]
Model compression for deep neural networks: A survey,
Z. Li, H. Li, and L. Meng, “Model compression for deep neural networks: A survey,” Computers, vol. 12, no. 3, p. 60, 2023
2023
-
[13]
Hyper-compression: Model compression via hyperfunction,
F. Fan, J. Fan, D. Wang, J. Zhang, Z. Dong, S. Zhang, G. Wang, and T. Zeng, “Hyper-compression: Model compression via hyperfunction,” arXiv preprint arXiv:2409.00592 , 2024
2024
-
[14]
Microsoft coco: Common objects in context,
T.-Y . Lin, M. Maire, S. Belongie, J. Hays, P. Perona, D. Ramanan, P. Doll ´ar, and C. L. Zitnick, “Microsoft coco: Common objects in context,” in Computer vision–ECCV 2014: 13th European conference, zurich, Switzerland, September 6-12, 2014, proceedings, part v 13 . Springer,...
2014
-
[15]
Lvis: A dataset for large vocabulary instance segmentation,
A. Gupta, P. Dollar, and R. Girshick, “Lvis: A dataset for large vocabulary instance segmentation,” in Proceedings of the IEEE/CVF conference on computer vision and pattern recognition, 2019, pp. 5356– 5364
2019
-
[16]
Sparsegpt: Massive language models can be accurately pruned in one-shot,
E. Frantar and D. Alistarh, “Sparsegpt: Massive language models can be accurately pruned in one-shot,” in International Conference on Machine Learning. PMLR, 2023, pp. 10 323–10 337
2023
-
[17]
Pruning neural networks without any data by iteratively conserving synaptic flow,
H. Tanaka, D. Kunin, D. L. Yamins, and S. Ganguli, “Pruning neural networks without any data by iteratively conserving synaptic flow,” Advances in neural information processing systems , vol. 33, pp. 6377– 6389, 2020
2020
-
[18]
The lottery ticket hypothesis: Finding sparse, trainable neural networks,
J. Frankle and M. Carbin, “The lottery ticket hypothesis: Finding sparse, trainable neural networks,” in International Conference on Learning Representations, 2018
2018
-
[19]
Autodfp: Automatic data-free pruning via channel similarity reconstruction,
S. Li, J. Chen, J. Xiang, C. Zhu, and Y . Liu, “Autodfp: Automatic data-free pruning via channel similarity reconstruction,” arXiv preprint arXiv:2403.08204, 2024
2024 arXiv
-
[20]
Billm: Pushing the limit of post-training quantization for llms,
W. Huang, Y . Liu, H. Qin, Y . Li, S. Zhang, X. Liu, M. Magno, and X. Qi, “Billm: Pushing the limit of post-training quantization for llms,” arXiv preprint arXiv:2402.04291 , 2024
2024 arXiv
-
[21]
Quantization and training of neural networks for efficient integer-arithmetic-only inference,
B. Jacob, S. Kligys, B. Chen, M. Zhu, M. Tang, A. Howard, H. Adam, and D. Kalenichenko, “Quantization and training of neural networks for efficient integer-arithmetic-only inference,” in Proceedings of the IEEE conference on computer vision and pattern recognition, 2018, pp. 2...
2018
-
[22]
Integer quanti- zation for deep learning inference: Principles and empirical evaluation,
H. Wu, P. Judd, X. Zhang, M. Isaev, and P. Micikevicius, “Integer quanti- zation for deep learning inference: Principles and empirical evaluation,” arXiv preprint arXiv:2004.09602 , 2020
2004 arXiv
-
[23]
Low-bit quantiza- tion of neural networks for efficient inference,
Y . Choukroun, E. Kravchik, F. Yang, and P. Kisilev, “Low-bit quantiza- tion of neural networks for efficient inference,” in 2019 IEEE/CVF In- ternational Conference on Computer Vision Workshop (ICCVW). IEEE, 2019, pp. 3009–3018
2019
-
[24]
Zeroq: A novel zero shot quantization framework,
Y . Cai, Z. Yao, Z. Dong, A. Gholami, M. W. Mahoney, and K. Keutzer, “Zeroq: A novel zero shot quantization framework,” in Proceedings of JOURNAL OF LATEX CLASS FILES, VOL. 14, NO. 8, AUGUST 2021 13 the IEEE/CVF conference on computer vision and pattern recognition , 2020, pp....
2021
-
[25]
Tensor-train decomposition,
I. V . Oseledets, “Tensor-train decomposition,” SIAM Journal on Scien- tific Computing, vol. 33, no. 5, pp. 2295–2317, 2011
2011
-
[26]
Tensor ring decomposition,
Q. Zhao, G. Zhou, S. Xie, L. Zhang, and A. Cichocki, “Tensor ring decomposition,” arXiv preprint arXiv:1606.05535 , 2016
2016 arXiv
-
[27]
Data- freeweight compress and denoise for large language models,
R. Peng, Y . Zhou, Q. Guo, Y . Gao, H. Yan, X. Qiu, and D. Lin, “Data- freeweight compress and denoise for large language models,” arXiv preprint arXiv:2402.16319, 2024
2024 arXiv
-
[28]
Distilling the knowledge in a neural network,
G. Hinton, O. Vinyals, and J. Dean, “Distilling the knowledge in a neural network,” arXiv preprint arXiv:1503.02531 , 2015
2015 arXiv
-
[29]
Faster segment anything: Towards lightweight sam for mobile applications,
C. Zhang, D. Han, Y . Qiao, J. U. Kim, S.-H. Bae, S. Lee, and C. S. Hong, “Faster segment anything: Towards lightweight sam for mobile applications,” arXiv preprint arXiv:2306.14289 , 2023
2023 arXiv
-
[30]
Ptq4sam: Post-training quantization for segment anything,
C. Lv, H. Chen, J. Guo, Y . Ding, and X. Liu, “Ptq4sam: Post-training quantization for segment anything,” in Proceedings of the IEEE/CVF Conference on Computer Vision and Pattern Recognition , 2024, pp. 15 941–15 951
2024
-
[31]
I. P. Cornfeld, S. V . Fomin, and Y . G. Sinai, Ergodic theory. Springer Science & Business Media, 2012, vol. 245
2012
-
[32]
Vector quantization,
R. Gray, “Vector quantization,” IEEE Assp Magazine , vol. 1, no. 2, pp. 4–29, 1984
1984
-
[33]
Qdrop: Randomly dropping quantization for extremely low-bit post-training quantization,
X. Wei, R. Gong, Y . Li, X. Liu, and F. Yu, “Qdrop: Randomly dropping quantization for extremely low-bit post-training quantization,” arXiv preprint arXiv:2203.05740, 2022
2022 arXiv
-
[34]
Exploring plain vision transformer backbones for object detection,
Y . Li, H. Mao, R. Girshick, and K. He, “Exploring plain vision transformer backbones for object detection,” in European conference on computer vision . Springer, 2022, pp. 280–296
2022
-
[35]
Yolox: Exceeding yolo series in 2021,
Z. Ge, S. Liu, F. Wang, Z. Li, and J. Sun, “Yolox: Exceeding yolo series in 2021,” arXiv preprint arXiv:2107.08430 , 2021
2021 arXiv
-
[36]
Up or down? adaptive rounding for post-training quantization,
M. Nagel, R. A. Amjad, M. Van Baalen, C. Louizos, and T. Blankevoort, “Up or down? adaptive rounding for post-training quantization,” in International conference on machine learning. PMLR, 2020, pp. 7197– 7206
2020
-
[37]
Brecq: Pushing the limit of post-training quantization by block reconstruction,
Y . Li, R. Gong, X. Tan, Y . Yang, P. Hu, Q. Zhang, F. Yu, W. Wang, and S. Gu, “Brecq: Pushing the limit of post-training quantization by block reconstruction,” arXiv preprint arXiv:2102.05426 , 2021
2021 arXiv
Reviewed August 6, 2026 · model on record in the stance chip above.
Discussion (0). Sign in to comment.