提出可证明收缩的去噪网络,提升图像恢复稳定性与质量。
Provably Contractive and High-Quality Denoisers for Convergent Restoration
- 通过展开技术构建带压缩控制的近端层,实现全局李普希茨常数小于1
- 在去噪任务中达到与顶级模型相当的性能,且对输入扰动的响应严格受限
- 适用于需要稳定收敛的插件式算法,适合对可靠性要求高的应用
图像恢复旨在从退化观测中重建干净图像,广泛应用于监控、国防和医学成像等领域。尽管现有卷积与注意力网络在性能上达到顶尖水平,但在输入发生微小变化时缺乏稳定性保障,存在鲁棒性与精度的权衡。本文提出可证明收缩(全局李普希茨常数<1)的去噪网络,显著缩小这一差距。设计基于展开技术获得的近端层,并引入李普希茨可控的卷积精修模块。由于收缩性保证,输入扰动强度‖δ‖≤ε时,输出变化不超过ε;而如DnCNN和Restormer等强基线模型在相同扰动下可能产生更大偏差。在图像去噪任务中,所提模型性能媲美无约束的顶流去噪器,为可证明1-李普希茨模型提供了最紧的误差间隙,证实此类性能差距确实可通过收缩去噪器实现。此外,该去噪器在插件式算法中作为强正则项,能保证收敛性。结果表明,严格李普希茨控制并不必然损害输出质量,挑战了文献中的常见假设,推动视觉模型向可验证、稳定方向发展。代码与预训练模型见https://github.com/SHUBHI1553/Contractive-Denoisers。
原文摘要 · Abstract (English)
Image restoration, the recovery of clean images from degraded measurements, has applications in various domains like surveillance, defense, and medical imaging. Despite achieving state-of-the-art (SOTA) restoration performance, existing convolutional and attention-based networks lack stability guarantees under minor shifts in input, exposing a robustness accuracy trade-off. We develop provably contractive (global Lipschitz $< 1$) denoiser networks that considerably reduce this gap. Our design composes proximal layers obtained from unfolding techniques, with Lipschitz-controlled convolutional refinements. By contractivity, our denoiser guarantees that input perturbations of strength $\|δ\|\le\varepsilon$ induce at most $\varepsilon$ change at the output, while strong baselines such as DnCNN and Restormer can exhibit larger deviations under the same perturbations. On image denoising, the proposed model is competitive with unconstrained SOTA denoisers, reporting the tightest gap for a provably 1-Lipschitz model and establishing that such gaps are indeed achievable by contractive denoisers. Moreover, the proposed denoisers act as strong regularizers for image restoration that provably effect convergence in Plug-and-Play algorithms. Our results show that enforcing strict Lipschitz control does not inherently degrade output quality, challenging a common assumption in the literature and moving the field toward verifiable and stable vision models. Codes and pretrained models are available at https://github.com/SHUBHI1553/Contractive-Denoisers
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