UniRL: Self-Improving Unified Multimodal Models via Supervised and Reinforcement Learning

Fuente: arXiv
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Main Authors: Mao, Weijia, Yang, Zhenheng, Shou, Mike Zheng
Format: Preprint
Published: 2025
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author Mao, Weijia
Yang, Zhenheng
Shou, Mike Zheng
author_facet Mao, Weijia
Yang, Zhenheng
Shou, Mike Zheng
contents Unified multimodal large language models such as Show-o and Janus have achieved strong performance across both generation and understanding tasks. However, these models typically rely on large-scale datasets and require substantial computation during the pretraining stage. In addition, several post-training methods have been proposed, but they often depend on external data or are limited to task-specific customization. In this work, we introduce UniRL, a self-improving post-training approach. Our approach enables the model to generate images from prompts and use them as training data in each iteration, without relying on any external image data. Moreover, it enables the two tasks to enhance each other: the generated images are used for understanding, and the understanding results are used to supervise generation. We explore supervised fine-tuning (SFT) and Group Relative Policy Optimization (GRPO) to optimize the models. UniRL offers three key advantages: (1) it requires no external image data, as all training samples are generated by the model itself during training; (2) it not only improves individual task performance, but also reduces the imbalance between generation and understanding; and (3) it requires only several additional training steps during the post-training stage. We evaluate UniRL on top of Show-o and Janus, achieving a GenEval score of 0.77 for Show-o and 0.65 for Janus. Code and models will be released in https://github.com/showlab/UniRL.
format Preprint
id arxiv_https___arxiv_org_abs_2505_23380
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle UniRL: Self-Improving Unified Multimodal Models via Supervised and Reinforcement Learning
Mao, Weijia
Yang, Zhenheng
Shou, Mike Zheng
Computer Vision and Pattern Recognition
Unified multimodal large language models such as Show-o and Janus have achieved strong performance across both generation and understanding tasks. However, these models typically rely on large-scale datasets and require substantial computation during the pretraining stage. In addition, several post-training methods have been proposed, but they often depend on external data or are limited to task-specific customization. In this work, we introduce UniRL, a self-improving post-training approach. Our approach enables the model to generate images from prompts and use them as training data in each iteration, without relying on any external image data. Moreover, it enables the two tasks to enhance each other: the generated images are used for understanding, and the understanding results are used to supervise generation. We explore supervised fine-tuning (SFT) and Group Relative Policy Optimization (GRPO) to optimize the models. UniRL offers three key advantages: (1) it requires no external image data, as all training samples are generated by the model itself during training; (2) it not only improves individual task performance, but also reduces the imbalance between generation and understanding; and (3) it requires only several additional training steps during the post-training stage. We evaluate UniRL on top of Show-o and Janus, achieving a GenEval score of 0.77 for Show-o and 0.65 for Janus. Code and models will be released in https://github.com/showlab/UniRL.
title UniRL: Self-Improving Unified Multimodal Models via Supervised and Reinforcement Learning
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2505.23380