IRPO: Boosting Image Restoration via Post-training GRPO

Fuente: arXiv
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Auteurs principaux: Xu, Haoxuan, Liu, Yi, Li, Tianfu, Shen, Ruolin, Jiang, Boyuan, Peng, Jinlong, Luo, Donghao, Hu, Xiaobin, Yan, Shuicheng, Li, Haoang
Format: Preprint
Publié: 2025
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author Xu, Haoxuan
Liu, Yi
Li, Tianfu
Shen, Ruolin
Jiang, Boyuan
Peng, Jinlong
Luo, Donghao
Hu, Xiaobin
Yan, Shuicheng
Li, Haoang
author_facet Xu, Haoxuan
Liu, Yi
Li, Tianfu
Shen, Ruolin
Jiang, Boyuan
Peng, Jinlong
Luo, Donghao
Hu, Xiaobin
Yan, Shuicheng
Li, Haoang
contents Post-training has become effective for high-level generation, but its role in low-level vision remains underexplored. Existing image restoration methods often rely on fixed pixel-wise fitting to ground-truth images, which can lead to over-smoothing and weak generalization. We propose IRPO, a GRPO-based post-training framework for deterministic restoration models. IRPO is built around two axes: data formulation and reward modeling. For data formulation, we select the 30% underperforming samples from the pre-training stage, which improves both accuracy and training efficiency. For reward modeling, we combine fidelity-oriented and quality-aware feedback with three components: a General Reward for structural fidelity, an Expert Reward that uses a Vision-Language Model as a coarse visual-quality judge, and a Restoration Reward for task-specific low-level cues. Experiments on six in-domain and five out-of-domain (OOD) benchmarks show that IRPO improves the AdaIR baseline by 0.93 dB on in-domain tasks and 3.43 dB on OOD settings. Our code can be shown in https://github.com/HaoxuanXU1024/IRPO.
format Preprint
id arxiv_https___arxiv_org_abs_2512_00814
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle IRPO: Boosting Image Restoration via Post-training GRPO
Xu, Haoxuan
Liu, Yi
Li, Tianfu
Shen, Ruolin
Jiang, Boyuan
Peng, Jinlong
Luo, Donghao
Hu, Xiaobin
Yan, Shuicheng
Li, Haoang
Computer Vision and Pattern Recognition
Post-training has become effective for high-level generation, but its role in low-level vision remains underexplored. Existing image restoration methods often rely on fixed pixel-wise fitting to ground-truth images, which can lead to over-smoothing and weak generalization. We propose IRPO, a GRPO-based post-training framework for deterministic restoration models. IRPO is built around two axes: data formulation and reward modeling. For data formulation, we select the 30% underperforming samples from the pre-training stage, which improves both accuracy and training efficiency. For reward modeling, we combine fidelity-oriented and quality-aware feedback with three components: a General Reward for structural fidelity, an Expert Reward that uses a Vision-Language Model as a coarse visual-quality judge, and a Restoration Reward for task-specific low-level cues. Experiments on six in-domain and five out-of-domain (OOD) benchmarks show that IRPO improves the AdaIR baseline by 0.93 dB on in-domain tasks and 3.43 dB on OOD settings. Our code can be shown in https://github.com/HaoxuanXU1024/IRPO.
title IRPO: Boosting Image Restoration via Post-training GRPO
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2512.00814