Paper Detail

Spectral Prior for Reducing Exposure Bias in Diffusion Models

Yuya Kobayashi, Masato Ishii, Yuhta Takida, Takashi Shibuya, Yuki Mitsufuji

huggingface Score 4.5

Published 2026-07-24 · First seen 2026-07-27

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Abstract

Diffusion models typically suffer from error accumulation during iterative sampling, commonly referred to as exposure bias. We reveal systematic frequency-dependent discrepancies between training and inference, which can be interpreted as frequency-dependent SNR error. Crucially, the direction of this mismatch varies across models and timesteps, indicating that fixed correction rules do not generalize. We propose Spectral Alignment (SPA), a lightweight, guidance-based method that calibrates the power spectrum of intermediate predictions to a pre-computed prior. Our approach consists of two stages: (1) offline fitting of a parametric spectrum model from training data, and (2) inference-time guidance via efficient FFT-based gradient computation. SPA introduces minimal computational overhead (3-4\%) and is complementary to Classifier-Free Guidance (CFG). We demonstrate consistent improvements across diverse architectures, from pixel-space models (DDPM, ADM) to latent diffusion models (SD2.0, SDXL) and flow-matching models (SD3.5, FLUX). Our implementation is available at https://github.com/SonyResearch/SPA.

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BibTeX

@misc{kobayashi2026spectral,
  title = {Spectral Prior for Reducing Exposure Bias in Diffusion Models},
  author = {Yuya Kobayashi and Masato Ishii and Yuhta Takida and Takashi Shibuya and Yuki Mitsufuji},
  year = {2026},
  abstract = {Diffusion models typically suffer from error accumulation during iterative sampling, commonly referred to as exposure bias. We reveal systematic frequency-dependent discrepancies between training and inference, which can be interpreted as frequency-dependent SNR error. Crucially, the direction of this mismatch varies across models and timesteps, indicating that fixed correction rules do not generalize. We propose Spectral Alignment (SPA), a lightweight, guidance-based method that calibrates the },
  url = {https://huggingface.co/papers/2607.22091},
  keywords = {code available, huggingface daily},
  eprint = {2607.22091},
  archiveprefix = {arXiv},
}

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