arXiv:2605.09433cs.CV2026-05中稿 · ICML被引 1

为流形生成模型设计了带噪声追踪的偏好优化方法,提升训练效率与稳定性。

Offline Preference Optimization for Rectified Flow with Noise-Tracked Pairs

论文配图:Offline Preference Optimization for Rectified Flow with Noise-Tracked Pairs
图 1 · 摘自论文原文
  • 用配对先验噪声扩展偏好数据,构建六元组增强训练信号
  • 利用流形直线路径特性插值中间状态,降低轨迹估计偏差
  • 动态调节正则化强度,适应奖励差距与训练进度,提升样本效率

现有文本到图像模型的偏好数据通常仅保存最终胜出/失败图像,这种表示方式对矩形流(RF)模型不充分,因其生成过程依赖特定先验噪声样本,并遵循近乎直线的去噪轨迹。传统DPO类对齐方法常使用独立前向加噪过程估计轨迹,与真实逆向动态不匹配,引入额外方差。本文提出先验噪声感知偏好优化(PNAPO),一种专用于矩形流的离线对齐框架。PNAPO通过保留生成每张胜出/失败图像所用的配对先验噪声,将标准三元组(提示,胜者,败者)扩展为六元组。利用矩形流的直线性质,通过噪声-图像插值估计中间状态,缩小轨迹估计空间,获得更紧致的代理目标。此外,引入动态正则化策略,根据胜败奖励差距和训练进度自适应调整DPO正则化强度,提升训练稳定性和样本效率。在先进的矩形流文本到图像骨干模型上实验表明,PNAPO在保持性能的同时显著降低训练计算开销。

原文摘要 · Abstract (English)

Existing preference datasets for text-to-image models typically store only the final winner/loser images. This representation is insufficient for rectified flow (RF) models, whose generation is naturally indexed by a specific prior noise sample and follows a nearly straight denoising trajectory. In contrast, prior DPO-style alignment for diffusion models commonly estimates trajectories using an independent forward noising process, which can be mismatched to the true reverse dynamics and introduces unnecessary variance. We propose Prior Noise-Aware Preference Optimization (PNAPO), an off-policy alignment framework specialized for rectified flow. PNAPO augments preference data by retaining the paired prior noises used to generate each winner/loser image, turning the standard (prompt, winner, loser) triplet into a sextuple. Leveraging the straight-line property of RF, we estimate intermediate states via noise-image interpolation, which constrains the trajectory estimation space and yields a tighter surrogate objective for preference optimization. In addition, we introduce a dynamic regularization strategy that adapts the DPO regularization based on (i) the reward gap between winner and loser and (ii) training progress, improving stability and sample efficiency. Experiments on state-of-the-art RF T2I backbones show that PNAPO consistently improves preference metrics while substantially reducing training compute.

生成模型偏好优化矩形流高效训练

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