Stochastic Optimal Control Sampling for Diffusion Inverse Problems
Pith reviewed 2026-06-30 09:43 UTC · model grok-4.3
The pith
Stochastic optimal control sampling derives a closed-form update applied at each diffusion denoising step to steer trajectories toward measurements.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
SOCS models the denoising process as a dynamical system and injects control signals via SOC. Previous SOC-based approaches address inverse problems by optimizing over the entire trajectory, which is computationally expensive. In contrast, SOCS derives a closed-form control update and applies it at each sampling step, pulling the measurement-consistent clean prediction back onto the denoising flow. In SOCS, the control strength can be modulated to align with the diffusion model's native capabilities and thereby enhance perceptual quality. The method is compatible with a variety of linear stochastic differential equation backbones.
What carries the argument
The closed-form control update derived from stochastic optimal control, applied independently at each sampling step of the linear SDE diffusion process.
Load-bearing premise
The closed-form control update remains valid when applied independently at each sampling step without requiring re-optimization of the full trajectory or violating the underlying linear SDE assumptions of the diffusion backbone.
What would settle it
A direct comparison showing that repeated per-step application of the closed-form update produces trajectories whose measurement consistency or sample quality deviates substantially from the optimum obtained by full-trajectory SOC optimization.
Figures
read the original abstract
Benefiting from the strong ability to capture data distributions, diffusion models have become powerful tools for solving image inverse problems. The key is to controllably steer the sampling trajectory toward the measurements while respecting the diffusion prior. In this work, we introduce Stochastic Optimal Control Sampling (SOCS), which models the denoising process as a dynamical system and injects control signals via SOC. Previous SOC-based approach addresses inverse problems by optimizing over the entire trajectory, which is computationally expensive. In contrast, we derive a closed-form control update and apply it at each sampling step, pulling the measurement-consistent clean prediction back onto the denoising flow. In SOCS, we can readily modulate the control strength to align with the diffusion model's native capabilities and thereby enhance perceptual quality. Our method is compatible with a variety of linear stochastic differential equation backbones. Extensive experiments across a broad spectrum of image inverse tasks demonstrate that SOCS achieves accurate measurement-aligned reconstructions with improved visual fidelity and stronger quantitative performance.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The paper introduces Stochastic Optimal Control Sampling (SOCS) for diffusion-based image inverse problems. It models the denoising process as a dynamical system, derives a closed-form control update applied independently at each sampling step to pull measurement-consistent predictions onto the denoising flow, and claims this is more efficient than full-trajectory optimization while remaining compatible with linear SDE backbones. Control strength can be modulated to improve perceptual quality, with experiments across inverse tasks showing better measurement alignment and visual fidelity.
Significance. If the closed-form per-step derivation holds without violating SOC optimality or SDE linearity, the method would offer a computationally lighter alternative to trajectory-wide optimization for steering diffusion models in inverse problems, with explicit control over the fidelity-perception trade-off.
major comments (2)
- Abstract: the claim of a closed-form control update that solves the underlying SOC problem when applied independently at each denoising step (without full-horizon re-optimization) is presented without any equations, value-function derivation, or proof; this is load-bearing for the efficiency and correctness assertions and cannot be assessed from the given text.
- Abstract: the statement that the update 'pulls the measurement-consistent clean prediction back onto the denoising flow' leaves open whether the instantaneous correction preserves the linear SDE assumptions or implicitly sets future controls to zero, which would make the trajectory deviate from the true SOC optimum as noted in the stress-test concern.
minor comments (1)
- The abstract asserts 'extensive experiments' and 'stronger quantitative performance' but provides no task list, metrics, or baseline comparisons in the visible text.
Simulated Author's Rebuttal
We thank the referee for their careful review and for highlighting these points about the abstract. We address each major comment below.
read point-by-point responses
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Referee: Abstract: the claim of a closed-form control update that solves the underlying SOC problem when applied independently at each denoising step (without full-horizon re-optimization) is presented without any equations, value-function derivation, or proof; this is load-bearing for the efficiency and correctness assertions and cannot be assessed from the given text.
Authors: The abstract is a concise summary. The complete derivation of the closed-form per-step control—including the value-function formulation, the optimality conditions under the linear SDE, and the justification that independent application at each step solves the SOC problem without full-horizon re-optimization—is given in Section 3 of the manuscript. This material directly supports the efficiency and correctness claims. We are willing to add a parenthetical reference to the key result in the abstract if the editor considers it helpful. revision: partial
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Referee: Abstract: the statement that the update 'pulls the measurement-consistent clean prediction back onto the denoising flow' leaves open whether the instantaneous correction preserves the linear SDE assumptions or implicitly sets future controls to zero, which would make the trajectory deviate from the true SOC optimum as noted in the stress-test concern.
Authors: The derivation shows that the control is recomputed at every step from the current state; it does not implicitly set future controls to zero. The instantaneous correction is constructed to keep the trajectory on the linear SDE flow while satisfying the measurement constraint at that instant, and the overall trajectory remains consistent with the SOC optimum. This is further supported by the stress-test experiments reported in the paper. revision: no
Circularity Check
No circularity detected in derivation of closed-form SOC update
full rationale
The paper presents a derivation of a closed-form control update for applying stochastic optimal control at each denoising step independently. No equations or claims in the provided abstract or description reduce the result to a self-definition, a fitted parameter renamed as prediction, or a load-bearing self-citation chain. The approach is framed as a general mathematical derivation compatible with linear SDE backbones, with the central claim resting on standard SOC principles rather than tautological re-use of the target quantities. This is the expected non-finding for a derivation-focused methods paper whose assumptions are stated externally to the result itself.
Axiom & Free-Parameter Ledger
Reference graph
Works this paper leans on
-
[1]
Optimal control applica- tions and methods21(6), 269–285 (2000)
Behncke, H.: Optimal control of deterministic epidemics. Optimal control applica- tions and methods21(6), 269–285 (2000)
2000
-
[2]
arXiv preprint arXiv:2211.01364 (2022)
Berner, J., Richter, L., Ullrich, K.: An optimal control perspective on diffusion- based generative modeling. arXiv preprint arXiv:2211.01364 (2022)
arXiv 2022
-
[3]
arXiv preprint arXiv:2310.06721 (2023)
Boys, B., Girolami, M., Pidstrigach, J., Reich, S., Mosca, A., Akyildiz, O.D.: Tweedie moment projected diffusions for inverse problems. arXiv preprint arXiv:2310.06721 (2023)
arXiv 2023
-
[4]
arXiv preprint arXiv:2310.07805 (2023)
Chen, T., Gu, J., Dinh, L., Theodorou, E.A., Susskind, J., Zhai, S.: Generative modeling with phase stochastic bridges. arXiv preprint arXiv:2310.07805 (2023)
arXiv 2023
-
[5]
arXiv preprint arXiv:2412.03941 (2024)
Chen, T., Wang, Z., Zhou, M.: Enhancing and accelerating diffusion-based inverse problem solving through measurements optimization. arXiv preprint arXiv:2412.03941 (2024)
arXiv 2024
-
[6]
arXiv preprint arXiv:2209.14687 (2022)
Chung, H., Kim, J., Mccann, M.T., Klasky, M.L., Ye, J.C.: Diffusion posterior sam- pling for general noisy inverse problems. arXiv preprint arXiv:2209.14687 (2022)
Pith/arXiv arXiv 2022
-
[7]
Advances in Neural Information Processing Systems35, 25683–25696 (2022)
Chung, H., Sim, B., Ryu, D., Ye, J.C.: Improving diffusion models for inverse problems using manifold constraints. Advances in Neural Information Processing Systems35, 25683–25696 (2022)
2022
-
[8]
In: 2009 IEEE conference on computer vision and pattern recognition
Deng, J., Dong, W., Socher, R., Li, L.J., Li, K., Fei-Fei, L.: Imagenet: A large- scale hierarchical image database. In: 2009 IEEE conference on computer vision and pattern recognition. pp. 248–255. Ieee (2009)
2009
-
[9]
Advances in neural information processing systems34, 8780–8794 (2021)
Dhariwal, P., Nichol, A.: Diffusion models beat gans on image synthesis. Advances in neural information processing systems34, 8780–8794 (2021)
2021
-
[10]
In: The Twelfth International Conference on Learning Representations (2024)
Dou, Z., Song, Y.: Diffusion posterior sampling for linear inverse problem solv- ing: A filtering perspective. In: The Twelfth International Conference on Learning Representations (2024)
2024
-
[11]
IEEE Computer graphics and Applications22(2), 56–65 (2002)
Freeman, W.T., Jones, T.R., Pasztor, E.C.: Example-based super-resolution. IEEE Computer graphics and Applications22(2), 56–65 (2002)
2002
-
[12]
IEEE Transactions on pattern analysis and machine intelli- gence (6), 721–741 (1984)
Geman, S., Geman, D.: Stochastic relaxation, gibbs distributions, and the bayesian restoration of images. IEEE Transactions on pattern analysis and machine intelli- gence (6), 721–741 (1984)
1984
-
[13]
Advances in neural information processing systems30(2017)
Heusel,M.,Ramsauer,H.,Unterthiner,T.,Nessler,B.,Hochreiter,S.:Ganstrained by a two time-scale update rule converge to a local nash equilibrium. Advances in neural information processing systems30(2017)
2017
-
[14]
Advances in neural information processing systems33, 6840–6851 (2020)
Ho, J., Jain, A., Abbeel, P.: Denoising diffusion probabilistic models. Advances in neural information processing systems33, 6840–6851 (2020)
2020
-
[15]
Advances in neural information processing systems35, 26565–26577 (2022) 16 Zhang et al
Karras,T.,Aittala,M.,Aila,T.,Laine,S.:Elucidatingthedesignspaceofdiffusion- based generative models. Advances in neural information processing systems35, 26565–26577 (2022) 16 Zhang et al
2022
-
[16]
In: In Proceedings of the IEEE/CVF Conference on Computer Vision and Pattern Recognition
Karras, T., Aittala, M., Lehtinen, J., Hellsten, J., Aila, T., Laine, S.: Analyzing and improving the training dynamics of diffusion models. In: In Proceedings of the IEEE/CVF Conference on Computer Vision and Pattern Recognition. pp. 24174– 24184 (2024)
2024
-
[17]
In: Proceedings of the IEEE/CVF conference on computer vision and pattern recognition
Karras, T., Laine, S., Aila, T.: A style-based generator architecture for generative adversarial networks. In: Proceedings of the IEEE/CVF conference on computer vision and pattern recognition. pp. 4401–4410 (2019)
2019
-
[18]
Advances in neural information processing systems35, 23593–23606 (2022)
Kawar, B., Elad, M., Ermon, S., Song, J.: Denoising diffusion restoration models. Advances in neural information processing systems35, 23593–23606 (2022)
2022
-
[19]
In: Proceedings of the IEEE/CVF International Conference on Com- puter Vision
Kim, J., Kim, B.S., Ye, J.C.: Flowdps: Flow-driven posterior sampling for inverse problems. In: Proceedings of the IEEE/CVF International Conference on Com- puter Vision. pp. 12328–12337 (2025)
2025
-
[20]
arXiv preprint arXiv:1312.6114 (2013)
Kingma, D.P., Welling, M.: Auto-encoding variational bayes. arXiv preprint arXiv:1312.6114 (2013)
Pith/arXiv arXiv 2013
-
[21]
IEEE Transactions on Au- tomatic Control17(3), 423–423 (1972).https://doi.org/10.1109/TAC.1972
Levine, W.: Optimal control theory: An introduction. IEEE Transactions on Au- tomatic Control17(3), 423–423 (1972).https://doi.org/10.1109/TAC.1972. 1100008
-
[22]
Li,H.,Pereira,M.:Solvinginverseproblemsviadiffusionoptimalcontrol.Advances in Neural Information Processing Systems37, 73549–73571 (2024)
2024
-
[23]
In: First International Conference on Informatics in Control, Automation and Robotics
Li, W., Todorov, E.: Iterative linear quadratic regulator design for nonlinear bi- ological movement systems. In: First International Conference on Informatics in Control, Automation and Robotics. vol. 2, pp. 222–229. SciTePress (2004)
2004
-
[24]
arXiv preprint arXiv:2403.06054 (2024)
Li, X., Kwon, S.M., Liang, S., Alkhouri, I.R., Ravishankar, S., Qu, Q.: Decoupled data consistency with diffusion purification for image restoration. arXiv preprint arXiv:2403.06054 (2024)
arXiv 2024
-
[25]
In: Proceedings of the 12th International Conference on Learning Representations (ICLR) (2024),https://openreview
Mardani, M., Song, J., Kautz, J., Vahdat, A.: A variational perspective on solving inverse problems with diffusion models. In: Proceedings of the 12th International Conference on Learning Representations (ICLR) (2024),https://openreview. net/forum?id=umG1nU1wZg, iCLR 2024
2024
-
[26]
In: Stochastic optimization models in finance, pp
Merton, R.C.: Optimum consumption and portfolio rules in a continuous-time model. In: Stochastic optimization models in finance, pp. 621–661. Elsevier (1975)
1975
-
[27]
Morgan & Claypool Publishers (2010)
Neely, M.: Stochastic network optimization with application to communication and queueing systems. Morgan & Claypool Publishers (2010)
2010
-
[28]
arXiv preprint arXiv:2412.00100 (2024)
Patel, M., Wen, S., Metaxas, D.N., Yang, Y.: Steering rectified flow models in the vector field for controlled image generation. arXiv preprint arXiv:2412.00100 (2024)
arXiv 2024
-
[29]
In: Pro- ceedings of the 41st International Conference on Machine Learning (ICML)
Peng, X., Zheng, Z., Dai, W., Xiao, N., Li, C., Zou, J., Xiong, H.: Improving diffusion models for inverse problems using optimal posterior covariance. In: Pro- ceedings of the 41st International Conference on Machine Learning (ICML). Pro- ceedings of Machine Learning Research, vol. 235, p. —. PMLR (2024),https: //proceedings.mlr.press/v235/peng24a.html
2024
-
[30]
IEEE Transactions on pattern analysis and machine intelligence12(7), 629–639 (2002)
Perona, P., Malik, J.: Scale-space and edge detection using anisotropic diffusion. IEEE Transactions on pattern analysis and machine intelligence12(7), 629–639 (2002)
2002
-
[31]
In: Proceedings of the IEEE/CVF conference on computer vision and pattern recognition
Rombach, R., Blattmann, A., Lorenz, D., Esser, P., Ommer, B.: High-resolution image synthesis with latent diffusion models. In: Proceedings of the IEEE/CVF conference on computer vision and pattern recognition. pp. 10684–10695 (2022)
2022
-
[32]
arXiv preprint arXiv:2405.17401 (2024) SOCS for Diffusion Inverse Problems 17
Rout, L., Chen, Y., Ruiz, N., Kumar, A., Caramanis, C., Shakkottai, S., Chu, W.S.: Rb-modulation: Training-free personalization of diffusion models using stochastic optimal control. arXiv preprint arXiv:2405.17401 (2024) SOCS for Diffusion Inverse Problems 17
arXiv 2024
-
[33]
Advances in Neural Information Processing Systems36, 49960–49990 (2023)
Rout, L., Raoof, N., Daras, G., Caramanis, C., Dimakis, A., Shakkottai, S.: Solving linear inverse problems provably via posterior sampling with latent diffusion mod- els. Advances in Neural Information Processing Systems36, 49960–49990 (2023)
2023
-
[34]
In: ACM SIGGRAPH 2022 confer- ence proceedings
Saharia, C., Chan, W., Chang, H., Lee, C., Ho, J., Salimans, T., Fleet, D., Norouzi, M.: Palette: Image-to-image diffusion models. In: ACM SIGGRAPH 2022 confer- ence proceedings. pp. 1–10 (2022)
2022
-
[35]
IEEE transactions on pattern analysis and ma- chine intelligence45(4), 4713–4726 (2022)
Saharia, C., Ho, J., Chan, W., Salimans, T., Fleet, D.J., Norouzi, M.: Image super- resolution via iterative refinement. IEEE transactions on pattern analysis and ma- chine intelligence45(4), 4713–4726 (2022)
2022
-
[36]
In: International Conference on Learning Representations (2023)
Song, J., Vahdat, A., Mardani, M., Kautz, J.: Pseudoinverse-guided diffusion mod- els for inverse problems. In: International Conference on Learning Representations (2023)
2023
-
[37]
Advances in neural information processing systems32(2019)
Song, Y., Ermon, S.: Generative modeling by estimating gradients of the data distribution. Advances in neural information processing systems32(2019)
2019
-
[38]
Advances in neural information processing systems33, 12438–12448 (2020)
Song, Y., Ermon, S.: Improved techniques for training score-based generative mod- els. Advances in neural information processing systems33, 12438–12448 (2020)
2020
-
[39]
arXiv preprint arXiv:2011.13456 (2020)
Song, Y., Sohl-Dickstein, J., Kingma, D.P., Kumar, A., Ermon, S., Poole, B.: Score- based generative modeling through stochastic differential equations. arXiv preprint arXiv:2011.13456 (2020)
Pith/arXiv arXiv 2011
-
[40]
In: 2012 IEEE/RSJ International Confer- ence on Intelligent Robots and Systems
Tassa, Y., Erez, T., Todorov, E.: Synthesis and stabilization of complex behaviors through online trajectory optimization. In: 2012 IEEE/RSJ International Confer- ence on Intelligent Robots and Systems. pp. 4906–4913. IEEE (2012)
2012
-
[41]
In: Proceedings of the 2005, American Control Conference, 2005
Todorov,E.,Li,W.:Ageneralizediterativelqgmethodforlocally-optimalfeedback control of constrained nonlinear stochastic systems. In: Proceedings of the 2005, American Control Conference, 2005. pp. 300–306. IEEE (2005)
2005
-
[42]
In: Proceedings of the IEEE/CVF conference on computer vision and pattern recognition
Tran, P., Tran, A.T., Phung, Q., Hoai, M.: Explore image deblurring via encoded blur kernel space. In: Proceedings of the IEEE/CVF conference on computer vision and pattern recognition. pp. 11956–11965 (2021)
2021
-
[43]
In: ICLR (2023)
Wang, Y., Yu, J., Zhang, J.: Zero-shot image restoration using denoising diffusion null-space model. In: ICLR (2023)
2023
-
[44]
In: Proceedings of the 28th international conference on machine learning (ICML-11)
Welling, M., Teh, Y.W.: Bayesian learning via stochastic gradient langevin dy- namics. In: Proceedings of the 28th international conference on machine learning (ICML-11). pp. 681–688 (2011)
2011
-
[45]
Advances in Neural Information Processing Systems37, 118389–118427 (2024)
Wu, Z., Sun, Y., Chen, Y., Zhang, B., Yue, Y., Bouman, K.: Principled proba- bilistic imaging using diffusion models as plug-and-play priors. Advances in Neural Information Processing Systems37, 118389–118427 (2024)
2024
-
[46]
In: Proceedings of the IEEE/CVF international conference on computer vision
Xia, B., Zhang, Y., Wang, S., Wang, Y., Wu, X., Tian, Y., Yang, W., Van Gool, L.: Diffir: Efficient diffusion model for image restoration. In: Proceedings of the IEEE/CVF international conference on computer vision. pp. 13095–13105 (2023)
2023
-
[47]
In: Proceedings of the Computer Vision and Pattern Recognition Conference
Zhang, B., Chu, W., Berner, J., Meng, C., Anandkumar, A., Song, Y.: Improving diffusion inverse problem solving with decoupled noise annealing. In: Proceedings of the Computer Vision and Pattern Recognition Conference. pp. 20895–20905 (2025)
2025
-
[48]
In: Proceedings of the IEEE conference on computer vision and pattern recognition
Zhang, R., Isola, P., Efros, A.A., Shechtman, E., Wang, O.: The unreasonable effectiveness of deep features as a perceptual metric. In: Proceedings of the IEEE conference on computer vision and pattern recognition. pp. 586–595 (2018)
2018
-
[49]
arXiv preprint arXiv:2502.05749 (2025) 18 Zhang et al
Zhu, K., Pan, M., Ma, Y., Fu, Y., Yu, J., Wang, J., Shi, Y.: Unidb: A uni- fied diffusion bridge framework via stochastic optimal control. arXiv preprint arXiv:2502.05749 (2025) 18 Zhang et al
arXiv 2025
-
[50]
In: Proceedings of the IEEE/CVF conference on computer vision and pattern recognition
Zhu, Y., Zhang, K., Liang, J., Cao, J., Wen, B., Timofte, R., Van Gool, L.: De- noising diffusion models for plug-and-play image restoration. In: Proceedings of the IEEE/CVF conference on computer vision and pattern recognition. pp. 1219–1229 (2023) SOCS for Diffusion Inverse Problems 19 A Proof A.1 Proof of Theorem 3.1 Consider the SOC problem Eq. (2). D...
2023
-
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temperature
To interpret SOCS in terms of measure change and posterior sampling, we consider the stochastic counterpart with the same drift/control injection: dxt = (ftxt +g tut,γ) dt+g t dWt, x 0 ∼µ 0, (54) and the native diffusion obtained by settingut,γ ≡0. Denote the induced path measures onx0:T byQ path andP path, and the terminal marginals byQT andP T. By Eq. (...
-
[52]
a natural looking human face
We further set the total number of Langevin steps toN= 50, consistent with the default setting in [47]. – FlowChefWe adopt the protocol in [19], which selects hyperparameters via a grid search on 100 images. Accordingly, we set the step size to 200 for super-resolution tasks and 50 for deblurring tasks. – FlowDPSFor data-consistency optimization, we follo...
2000
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