Papers › SRFlow: Learning the Super-Resolution Space with Normalizing Flow
SRFlow: Learning the Super-Resolution Space with Normalizing Flow
Andreas Lugmayr, Martin Danelljan, Luc van Gool, Radu Timofte
Super-resolution is an ill-posed problem, since it allows for multiple predictions for a given low-resolution image. This fundamental fact is largely ignored by state-of-the-art deep learning based approaches. These methods instead train a deterministic mapping using combinations of reconstruction and adversarial losses. In this work, we therefore propose SRFlow: a normalizing flow based super-resolution method capable of learning the conditional distribution of the output given the low-resolution input. Our model is trained in a principled manner using a single loss, namely the negative log-likelihood. SRFlow therefore directly accounts for the ill-posed nature of the problem, and learns to predict diverse photo-realistic high-resolution images. Moreover, we utilize the strong image posterior learned by SRFlow to design flexible image manipulation techniques, capable of enhancing super-resolved images by, e.g., transferring content from other images. We perform extensive experiments on faces, as well as on super-resolution in general. SRFlow outperforms state-of-the-art GAN-based approaches in terms of both PSNR and perceptual quality metrics, while allowing for diversity through the exploration of the space of super-resolved solutions.
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Tasks
Results from the paper archive 2025-07-28
| Task | Dataset | Model | Metric | Value | Rank at snapshot | Leaderboard | Report |
|---|---|---|---|---|---|---|---|
| Image Super-Resolution | DIV2K val - 4x upscaling | SRFlow | LPIPS | 0.12 | #8 of 21 | Archive leaderboard | report |
| Image Super-Resolution | DIV2K val - 4x upscaling | SRFlow | LRPSNR | 49.96 | #8 of 21 | Archive leaderboard | report |
| Image Super-Resolution | DIV2K val - 4x upscaling | SRFlow | NIQE | 3.57 | #8 of 21 | Archive leaderboard | report |
| Image Super-Resolution | DIV2K val - 4x upscaling | SRFlow | PSNR | 27.09 | #8 of 21 | Archive leaderboard | report |
| Image Super-Resolution | DIV2K val - 4x upscaling | SRFlow | SSIM | 0.76 | #8 of 21 | Archive leaderboard | report |
Ranks are positions in the archive's leaderboards as they stood at the 2025-07-28 snapshot. Results published since then are not among these rows, so a rank here is not a current standing.
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