MaskFocus: Focusing Policy Optimization on Critical Steps for Masked Image Generation

Fuente: arXiv
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Autori principali: Zhang, Guohui, Yu, Hu, Ma, Xiaoxiao, Pan, Yaning, Xu, Hang, Zhao, Feng
Natura: Preprint
Pubblicazione: 2025
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author Zhang, Guohui
Yu, Hu
Ma, Xiaoxiao
Pan, Yaning
Xu, Hang
Zhao, Feng
author_facet Zhang, Guohui
Yu, Hu
Ma, Xiaoxiao
Pan, Yaning
Xu, Hang
Zhao, Feng
contents Reinforcement learning (RL) has demonstrated significant potential for post-training language models and autoregressive visual generative models, but adapting RL to masked generative models remains challenging. The core factor is that policy optimization requires accounting for the probability likelihood of each step due to its multi-step and iterative refinement process. This reliance on entire sampling trajectories introduces high computational cost, whereas natively optimizing random steps often yields suboptimal results. In this paper, we present MaskFocus, a novel RL framework that achieves effective policy optimization for masked generative models by focusing on critical steps. Specifically, we determine the step-level information gain by measuring the similarity between the intermediate images at each sampling step and the final generated image. Crucially, we leverage this to identify the most critical and valuable steps and execute focused policy optimization on them. Furthermore, we design a dynamic routing sampling mechanism based on entropy to encourage the model to explore more valuable masking strategies for samples with low entropy. Extensive experiments on multiple Text-to-Image benchmarks validate the effectiveness of our method.
format Preprint
id arxiv_https___arxiv_org_abs_2512_18766
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle MaskFocus: Focusing Policy Optimization on Critical Steps for Masked Image Generation
Zhang, Guohui
Yu, Hu
Ma, Xiaoxiao
Pan, Yaning
Xu, Hang
Zhao, Feng
Computer Vision and Pattern Recognition
Reinforcement learning (RL) has demonstrated significant potential for post-training language models and autoregressive visual generative models, but adapting RL to masked generative models remains challenging. The core factor is that policy optimization requires accounting for the probability likelihood of each step due to its multi-step and iterative refinement process. This reliance on entire sampling trajectories introduces high computational cost, whereas natively optimizing random steps often yields suboptimal results. In this paper, we present MaskFocus, a novel RL framework that achieves effective policy optimization for masked generative models by focusing on critical steps. Specifically, we determine the step-level information gain by measuring the similarity between the intermediate images at each sampling step and the final generated image. Crucially, we leverage this to identify the most critical and valuable steps and execute focused policy optimization on them. Furthermore, we design a dynamic routing sampling mechanism based on entropy to encourage the model to explore more valuable masking strategies for samples with low entropy. Extensive experiments on multiple Text-to-Image benchmarks validate the effectiveness of our method.
title MaskFocus: Focusing Policy Optimization on Critical Steps for Masked Image Generation
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2512.18766