Omni-RRM: Advancing Omni Reward Modeling via Automatic Rubric-Grounded Preference Synthesis
Summary
Omni-RRM is the first open-source rubric-grounded reward model designed to enhance multimodal large language models (MLLMs) by providing structured, multi-dimension preference judgments with justifications across text, image, video, and audio. It addresses limitations of existing vision-centric reward models (RMs) that often return opaque scalar scores and rely on costly human annotations. Omni-RRM is trained on Omni-Preference, a large-scale dataset of approximately 41K preference examples, built via a fully automated pipeline using strong teacher models for rubric-grounded rationales. The model achieves state-of-the-art accuracy on video (80.2% on ShareGPT-V) and audio (66.8% on Audio-HH-RLHF) benchmarks, and a 17.7% absolute gain over its base model on image tasks. It also improves downstream performance via Best-of-$N$ selection and transfers to text-only preference benchmarks.
Key takeaway
For AI Scientists and ML Engineers developing multimodal LLMs, Omni-RRM offers a robust solution for alignment. Its rubric-grounded, multi-dimensional feedback provides clear insights into model errors, surpassing opaque scalar scores. You should consider integrating Omni-RRM to enhance model interpretability, reduce reliance on costly human annotation, and achieve state-of-the-art performance across diverse modalities, including audio and video. This approach can significantly improve the reliability and trustworthiness of your MLLM deployments.
Key insights
Omni-RRM provides structured, rubric-grounded multimodal preference judgments without human annotation.
Principles
- Rubric-structured feedback improves MLLM alignment and interpretability.
- Automated data synthesis can replace costly human annotation for reward models.
- Unified reward models benefit lower-resource modalities through cross-modal supervision.
Method
Omni-RRM is trained in two stages: Supervised Fine-Tuning (SFT) for rubric-grounded output, then Group Relative Policy Optimization (GRPO) to sharpen discrimination on low-contrast pairs.
In practice
- Use Omni-RRM for fine-grained MLLM error resolution across modalities.
- Apply Best-of-$N$ selection with Omni-RRM to improve MLLM inference performance.
- Explore automated rubric-grounded data generation for custom alignment tasks.
Topics
- Omni-RRM
- Multimodal LLMs
- Reward Models
- Preference Alignment
- Rubric-Grounded Feedback
- Automated Data Synthesis
- Reinforcement Learning
Best for: Research Scientist, AI Scientist, Machine Learning Engineer, AI Engineer
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Editorial summary, takeaway, and curation by AIssential. Original article published by cs.CL updates on arXiv.org.