Fourier Priors-Guided Diffusion for Zero-Shot Joint Low-Light Enhancement and Deblurring
Xiaoqian LvShengping ZhangChenyang WangYichen ZhengBineng ZhongChongyi LiLiqiang Nie
Proposes FourierDiff, a zero-shot framework that integrates Fourier amplitude and phase priors into pre-trained diffusion models to jointly brighten dark images and remove motion blur without requiring paired training data or explicit degradation assumptions.
Low-light photography frequently suffers from simultaneous degradation: limited illumination and severe motion blur caused by long camera exposure times. Traditional image processing methods usually tackle brightness enhancement and deblurring separately or rely heavily on synthetic training data and assumed degradation models. When applied to complex real-world night photography, existing techniques often create severe visual artifacts, introduce color distortion, or fail to remove blur.
The article introduces and evaluates FourierDiff, a novel zero-shot framework that performs joint low-light enhancement and motion deblurring without requiring paired training data or predefined degradation assumptions. The framework leverages the frequency domain by separating brightness information into Fourier amplitudes and structural content into Fourier phases, using a pre-trained diffusion model to restore degraded images.
The authors evaluated the framework across standard synthetic datasets (12,000 image pairs from LOL-Blur) and real-world benchmarks (482 test images from RealBlur) using standard blind perceptual quality metrics (NIQE, PI, BRISQUE, and MUSIQ) alongside full-reference metrics. An unconditional diffusion model pre-trained on ImageNet served as the foundation, paired with an alternating optimization strategy designed to iteratively refine blur kernel estimation during the diffusion reverse sampling process. A subjective user study involving 40 participants across 20 test scenes was also conducted to gauge visual preference.
The evaluation yielded several key findings. First, the proposed framework outperformed all state-of-the-art baselines across every no-reference perceptual quality metric on both synthetic and real-world datasets, achieving top scores such as a RealBlur BRISQUE score of 26.39 compared to 34.80–45.89 for competing sequential and joint pipelines. Second, the method achieved results comparable to fully supervised methods on synthetic benchmarks while generalizing substantially better to real-world night scenes without generating artificial halos or excessive noise. Third, human evaluation showed a decisive preference for the approach, with participants favoring the proposed method over competing methods in 70.5% to 97.0% of visual comparisons. Finally, an ablation analysis demonstrated that updating blur kernel estimates during diffusion sampling produced clear performance improvements, with optimal efficiency and quality achieved at an alternating step interval of 200.
These results demonstrate that separating image restoration tasks into distinct frequency components allows pre-trained generative models to restore complex, real-world image degradations without the risk of overfitting associated with synthetic training pairs. Eliminating the requirement for specialized paired datasets significantly reduces development costs and deployment risks for computer vision applications operating in adverse, low-light environments, such as surveillance, night-time action recognition, and autonomous navigation.
Organizations seeking to enhance image quality in low-light environments should consider adopting frequency-guided zero-shot diffusion pipelines over rigid, supervised networks, especially where diverse and unmodeled real-world blur is present. To implement this approach effectively, practitioners should incorporate adjustable brightness parameters to tune outputs according to specific operational needs.
While the framework shows high efficacy on standard night-time imagery, confidence should be tempered in scenarios involving extreme darkness, where the complete loss of initial content guidance degrades structural reconstruction. Additionally, because the architecture relies on iterative diffusion sampling over hundreds of steps, high computational latency remains a limitation that currently precludes real-time deployment without further optimization.
- Paper: Zero-Shot Image Restoration Using Denoising Diffusion Null-Space Model, Yinhuai Wang et al. (2023). Provides the foundational zero-shot image restoration framework using pre-trained diffusion models and null-space decomposition that FourierDiff directly builds upon.
- Paper: Diffusion Posterior Sampling for General Noisy Inverse Problems, Hyungjin Chung et al. (2022). Introduces posterior sampling for general noisy inverse problems in diffusion models, establishing the mathematical groundwork for using generative priors to solve degradation tasks.
- Paper: Denoising Diffusion Restoration Models, Bahjat Kawar et al. (2022). Demonstrates how pre-trained diffusion models can be repurposed for unsupervised linear inverse image restoration without task-specific retraining.
- Paper: Denoising Diffusion Implicit Models, Jiaming Song et al. (2021). Introduces non-Markovian deterministic sampling for diffusion models, which forms the standard reverse sampling mechanics leveraged by zero-shot diffusion restoration techniques.
- Paper: Denoising Diffusion Probabilistic Models, Jonathan Ho et al. (2020). Presents the foundational denoising diffusion probabilistic model paradigm on which pre-trained generative diffusion priors are constructed.
- Paper: Zero-Reference Deep Curve Estimation for Low-Light Image Enhancement, Chunle Guo et al. (2020). Introduces non-reference curve estimation concepts for low-light enhancement without paired training data, setting the standard for zero-shot illumination adjustment.
- Paper: Fast Image Deconvolution using Hyper-Laplacian Priors, Dilip Krishnan et al. (2009). Pioneers alternating optimization in the frequency domain for image deconvolution, motivating FourierDiff's spatial-frequency alternating optimization strategy.
- Paper: Variational Flow Maps: Make Some Noise for One-Step Conditional Generation, Abbas Mammadov et al. (2026). Extends conditional inverse problem solving beyond multi-step diffusion sampling by learning variational flow maps for accelerated one-step conditional generation.
- Paper: An exact information theory of generalization phase transitions in Bayesian diffusion models, Henry Hunt et al. (2026). Provides theoretical information-theoretic foundations and generalization bounds for how Bayesian diffusion priors operate across image restoration settings.
