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Residual-Conditioned Optimal Transport: Towards Structure-Preserving Unpaired and Paired Image Restoration

5 May 2024arXiv:2405.02843archive 2025-07-28

Xiaole Tang, Xin Hu, Xiang Gu, Jian Sun

Deep learning-based image restoration methods generally struggle with faithfully preserving the structures of the original image. In this work, we propose a novel Residual-Conditioned Optimal Transport (RCOT) approach, which models image restoration as an optimal transport (OT) problem for both unpaired and paired settings, introducing the transport residual as a unique degradation-specific cue for both the transport cost and the transport map. Specifically, we first formalize a Fourier residual-guided OT objective by incorporating the degradation-specific information of the residual into the transport cost. We further design the transport map as a two-pass RCOT map that comprises a base model and a refinement process, in which the transport residual is computed by the base model in the first pass and then encoded as a degradation-specific embedding to condition the second-pass restoration. By duality, the RCOT problem is transformed into a minimax optimization problem, which can be solved by adversarially training neural networks. Extensive experiments on multiple restoration tasks show that RCOT achieves competitive performance in terms of both distortion measures and perceptual quality, restoring images with more faithful structures as compared with state-of-the-art methods.

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Code

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CALayer xl-tang3/RCOT/Net.py official repository ran · metamorphic tier: deterministic no licence file found · pointer only · d487b4aabe9c084e · report
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get_parameter_number xl-tang3/RCOT/trainer.py official repository ran · honoured contract no licence file found · pointer only · a23501ebdd938df8 · report
T_net xl-tang3/RCOT/Net.py official repository unverified no licence file found · pointer only · 21d9b606fd0956a1 · report
PSNR xl-tang3/DA-RCOT/tester.py community ran · our draft was wrong MIT (permissive) · f4c99d0f2598f605 · report
conv identical code first harvested elsewhere ran · our draft was wrong licence of this copy not recorded · ad4c565716dab068 · report

Tasks

Color Image DenoisingImage RestorationImage Super-Resolution

Results from the paper archive 2025-07-28

TaskDatasetModelMetricValueRank at snapshotLeaderboardReport
Color Image Denoising CBSD68 sigma50 RCOT PSNR 28.25 #8 of 18 Archive leaderboard report
Image Super-Resolution DIV2K val - 4x upscaling RCOT LPIPS 0.104 #4 of 21 Archive leaderboard report
Image Super-Resolution DIV2K val - 4x upscaling RCOT PSNR 28.41 #4 of 21 Archive leaderboard report
Image Super-Resolution DIV2K val - 4x upscaling RCOT SSIM 0.804 #4 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.

Methods

BASE

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