SCoRe: Clean Image Generation from Diffusion Models Trained on Noisy Images

Yuta Matsuzaki; Seiichi Uchida; Shumpei Takezaki

cs.CVApr 10, 2026

SCoRe: Clean Image Generation from Diffusion Models Trained on Noisy Images

Authors: Yuta Matsuzaki, Seiichi Uchida, Shumpei Takezaki

Organizations: Kyushu University, Fukuoka, Japan

Abstract

Diffusion models trained on noisy datasets often reproduce high-frequency training artifacts, significantly degrading generation quality. To address this, we propose SCoRe (Spectral Cutoff Regeneration), a training-free, generation-time spectral regeneration method for clean image generation from diffusion models trained on noisy images. Leveraging the spectral bias of diffusion models, which infer high-frequency details from low-frequency cues, SCoRe suppresses corrupted high-frequency components of a generated image via a frequency cutoff and regenerates them via SDEdit. Crucially, we derive a theoretical mapping between the cutoff frequency and the SDEdit initialization timestep based on Radially Averaged Power Spectral Density (RAPSD), which prevents excessive noise injection during regeneration. Experiments on synthetic (CIFAR-10) and real-world (SIDD) noisy datasets demonstrate that SCoRe substantially outperforms post-processing and noise-robust baselines, restoring samples closer to clean image distributions without any retraining or fine-tuning.

Figures & tables

Fig. 1: Impact of a dataset containing noisy training images on the generated results. Images in red boxes are clean examples; all others are noisy.

Fig. 2: (a) Overview of the diffusion and reverse processes in terms of frequency components. (b) SCoRe : training-free, generation-time spectral regeneration that suppresses high-frequency components via a frequency cutoff and regenerates high-frequency details via SDEdit.

Fig. 3: The generation process of a diffusion model trained on noisy images. (a) Standard generation process: produces noisy generated images. (b) SDEdit: When SDEdit is applied to a noisy generated image, the result is regenerated as a noisy image. (c) SCoRe: Removal of high-frequency components via a cutoff operation, followed by regeneration using SDEdit to yield cleaner images.

Fig. 4: Generated images under CIFAR-10 with Gaussian noise: (a) Training examples, (b) standard diffusion sampling, (c) generated images post-processed with a bilateral filter, (d) generated images post-processed with Noise2Void, (e) NR-GAN, and (f) SCoRe.

Fig. 5: Comparison of the RAPSDs of clean images, training images, and the results produced by the proposed method under Gaussian noise.

Method	Gaussian	Poisson	Mix
Diffusion Model	132.9	168.7	203.2
w/ Post-Bilateral	51.7	68.0	102.8
w/ Post-N2V	32.3	31.6	40.1
SDEdit	132.2	151.3	180.2
NR-GAN	15.5	46.5	32.0
SCoRe ( $f_{\mathrm{cutoff}}=0.20$ , $t^{\prime}=119$ )	14.0	14.9	16.2

TABLE I: Comparison of FID on synthetic noisy dataset

Fig. 6: Effect of the noisy-data ratio in training on FID (x-axis: percentage of noisy training images).

Fig. 7: Generated Results : (a) training examples, (b) standard diffusion sampling, (c) generated images post-processed with a bilateral filter, (d) generated images post-processed with Noise2Void, (e) NR-GAN, and (f) SCoRe.

Method	SIDD
Diffusion Model	30.1
w/ Post-Bilateral	30.9
w/ Post-N2V	27.0
SDEdit	30.6
NR-GAN	46.3
SCoRe ( $f_{\mathrm{cutoff}}=0.05$ , $t^{\prime}=110$ )	29.0

TABLE II: Comparison of FID on real-world noisy dataset

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Diffusion models have been shown to implicitly generate visual content autoregressively in the frequency domain, where low-frequency components are generated earlier in the denoising process while high-frequency details emerge only in later timesteps. This structure offers a natural opportunity for efficient generation, as high-resolution computation on noise-dominated frequencies is largely redundant. We propose Spectral Progressive Diffusion, a general framework that progressively grows resolution along the denoising trajectory of pretrained diffusion models. To this end, we develop a spectral noise expansion mechanism and derive an optimal resolution schedule from the model's power spectrum. Our framework supports training-free acceleration and a novel fine-tuning recipe that further improves efficiency and quality. We demonstrate significant speedups on state-of-the-art pretrained image and video generation models while preserving visual quality.

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