arXiv:2510.23588cs.CV2025-10被引 16

将流模型与自回归结合,直接从像素生成高质量图像并计算精确概率。

FARMER: Flow AutoRegressive Transformer over Pixels

  • 用可逆自回归流将图像转为潜在序列,再用自回归建模其分布。
  • 通过自监督降维减少冗余,提升建模效率;推理速度显著加快。
  • 支持无分类器引导生成,适合需要精确概率的图像生成任务。

直接建模原始数据分布的显式似然性是机器学习中的核心课题,大语言模型的成功得益于自回归建模的扩展性。然而,在视觉像素数据上进行连续自回归建模面临序列过长和高维空间的挑战。本文提出FARMER,一种统一归一化流(NF)与自回归(AR)的端到端生成框架,实现对原始像素的可解析似然估计与高质量图像合成。FARMER利用可逆自回归流将图像映射至潜在序列,其分布由自回归模型隐式建模。为解决像素级建模中的冗余与复杂性,提出自监督维度缩减方案,将流模型潜变量通道分为信息与冗余组,提升自回归建模的有效性与效率。此外,设计单步蒸馏方案显著加速推理,并引入基于重采样的无分类器引导算法提升生成质量。大量实验表明,FARMER在性能上媲美现有像素级生成模型,同时提供精确似然值且支持可扩展训练。

原文摘要 · Abstract (English)

Directly modeling the explicit likelihood of the raw data distribution is key topic in the machine learning area, which achieves the scaling successes in Large Language Models by autoregressive modeling. However, continuous AR modeling over visual pixel data suffer from extremely long sequences and high-dimensional spaces. In this paper, we present FARMER, a novel end-to-end generative framework that unifies Normalizing Flows (NF) and Autoregressive (AR) models for tractable likelihood estimation and high-quality image synthesis directly from raw pixels. FARMER employs an invertible autoregressive flow to transform images into latent sequences, whose distribution is modeled implicitly by an autoregressive model. To address the redundancy and complexity in pixel-level modeling, we propose a self-supervised dimension reduction scheme that partitions NF latent channels into informative and redundant groups, enabling more effective and efficient AR modeling. Furthermore, we design a one-step distillation scheme to significantly accelerate inference speed and introduce a resampling-based classifier-free guidance algorithm to boost image generation quality. Extensive experiments demonstrate that FARMER achieves competitive performance compared to existing pixel-based generative models while providing exact likelihoods and scalable training.

图像生成自回归归一化流像素建模

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