Arena as Offline Reward: Efficient Fine-Grained Preference Optimization for Diffusion Models

Fuente: arXiv
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Main Authors: Li, Zhikai, Zhao, Yue, Zhang, Edward Zhongwei, Liu, Xuewen, Zhang, Jing, Gu, Qingyi, Dong, Zhen
Format: Preprint
Published: 2026
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author Li, Zhikai
Zhao, Yue
Zhang, Edward Zhongwei
Liu, Xuewen
Zhang, Jing
Gu, Qingyi
Dong, Zhen
author_facet Li, Zhikai
Zhao, Yue
Zhang, Edward Zhongwei
Liu, Xuewen
Zhang, Jing
Gu, Qingyi
Dong, Zhen
contents Reinforcement learning from human feedback (RLHF) effectively promotes preference alignment of text-to-image (T2I) diffusion models. To improve computational efficiency, direct preference optimization (DPO), which avoids explicit reward modeling, has been widely studied. However, its reliance on binary feedback limits it to coarse-grained modeling on chosen-rejected pairs, resulting in suboptimal optimization. In this paper, we propose ArenaPO, which leverages Arena scores as offline rewards to provide refined feedback, thus achieving efficient and fine-grained optimization without a reward model. This enables ArenaPO to benefit from both the rich rewards of traditional RLHF and the efficiency of DPO. Specifically, we first construct a model Arena in which each model's capability is represented as a Gaussian distribution, and infer these capabilities by traversing the annotated pairwise preferences. Each output image is treated as a sample from the corresponding capability distribution. Then, for a image pair, conditioned on the two capability distributions and the observed pairwise preference, the absolute quality gap is estimated using latent-variable inference based on truncated normal distribution, which serves as fine-grained feedback during training. It does not require a reward model and can be computed offline, thus introducing no additional training overhead. We conduct ArenaPO training on Pick-a-Pic v2 and HPD v3 datasets, showing that ArenaPO consistently outperforms existing baselines.
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id arxiv_https___arxiv_org_abs_2605_06070
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publishDate 2026
record_format arxiv
spellingShingle Arena as Offline Reward: Efficient Fine-Grained Preference Optimization for Diffusion Models
Li, Zhikai
Zhao, Yue
Zhang, Edward Zhongwei
Liu, Xuewen
Zhang, Jing
Gu, Qingyi
Dong, Zhen
Computer Vision and Pattern Recognition
Reinforcement learning from human feedback (RLHF) effectively promotes preference alignment of text-to-image (T2I) diffusion models. To improve computational efficiency, direct preference optimization (DPO), which avoids explicit reward modeling, has been widely studied. However, its reliance on binary feedback limits it to coarse-grained modeling on chosen-rejected pairs, resulting in suboptimal optimization. In this paper, we propose ArenaPO, which leverages Arena scores as offline rewards to provide refined feedback, thus achieving efficient and fine-grained optimization without a reward model. This enables ArenaPO to benefit from both the rich rewards of traditional RLHF and the efficiency of DPO. Specifically, we first construct a model Arena in which each model's capability is represented as a Gaussian distribution, and infer these capabilities by traversing the annotated pairwise preferences. Each output image is treated as a sample from the corresponding capability distribution. Then, for a image pair, conditioned on the two capability distributions and the observed pairwise preference, the absolute quality gap is estimated using latent-variable inference based on truncated normal distribution, which serves as fine-grained feedback during training. It does not require a reward model and can be computed offline, thus introducing no additional training overhead. We conduct ArenaPO training on Pick-a-Pic v2 and HPD v3 datasets, showing that ArenaPO consistently outperforms existing baselines.
title Arena as Offline Reward: Efficient Fine-Grained Preference Optimization for Diffusion Models
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2605.06070