Papers › Low-Light Image Enhancement with Normalizing Flow

Low-Light Image Enhancement with Normalizing Flow

13 Sep 2021arXiv:2109.05923archive 2025-07-28

YuFei Wang, Renjie Wan, Wenhan Yang, Haoliang Li, Lap-Pui Chau, Alex C. Kot

To enhance low-light images to normally-exposed ones is highly ill-posed, namely that the mapping relationship between them is one-to-many. Previous works based on the pixel-wise reconstruction losses and deterministic processes fail to capture the complex conditional distribution of normally exposed images, which results in improper brightness, residual noise, and artifacts. In this paper, we investigate to model this one-to-many relationship via a proposed normalizing flow model. An invertible network that takes the low-light images/features as the condition and learns to map the distribution of normally exposed images into a Gaussian distribution. In this way, the conditional distribution of the normally exposed images can be well modeled, and the enhancement process, i.e., the other inference direction of the invertible network, is equivalent to being constrained by a loss function that better describes the manifold structure of natural images during the training. The experimental results on the existing benchmark datasets show our method achieves better quantitative and qualitative results, obtaining better-exposed illumination, less noise and artifact, and richer colors.

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wyf0912/LLFlow officialmentioned on GitHubpytorchNOASSERTION report

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Tasks

Image EnhancementLow-Light Image Enhancement

Results from the paper archive 2025-07-28

TaskDatasetModelMetricValueRank at snapshotLeaderboardReport
Low-Light Image Enhancement LOL LLFlow Average PSNR 25.19 #17 of 40 Archive leaderboard report
Low-Light Image Enhancement LOL LLFlow LPIPS 0.11 #17 of 40 Archive leaderboard report
Low-Light Image Enhancement LOL LLFlow SSIM 0.93 #17 of 40 Archive leaderboard report
Low-Light Image Enhancement LOLv2 LLFlow Average PSNR 26.02 #11 of 12 Archive leaderboard report
Low-Light Image Enhancement LOLv2 LLFlow LPIPS 0.0995 #11 of 12 Archive leaderboard report
Low-Light Image Enhancement LOLv2 LLFlow SSIM 0.927 #11 of 12 Archive leaderboard report
Low-Light Image Enhancement Sony-Total-Dark LLFlow Average PSNR 16.226 #3 of 3 Archive leaderboard report
Low-Light Image Enhancement Sony-Total-Dark LLFlow LPIPS 0.619 #3 of 3 Archive leaderboard report
Low-Light Image Enhancement Sony-Total-Dark LLFlow SSIM 0.367 #3 of 3 Archive leaderboard report

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