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MLLM-as-a-Judge: Assessing Multimodal LLM-as-a-Judge with Vision-Language Benchmark

Paper · 2024 · Dongping Chen, Ruoxi Chen, Shilin Zhang et al.

Summary

Automatic metrics for multimodal model outputs, such as exact matching or embedding similarity, miss fine-grained quality criteria. This paper asks whether multimodal LLMs can take over the evaluator role that text-only LLMs already play, and how well their verdicts agree with people. The authors build the MLLM-as-a-Judge benchmark. They collected 4,414 image-instruction pairs from 14 source datasets covering captioning, math, charts, text reading, diffusion and other tasks. Six MLLMs answered these pairs, producing about 17,000 responses. Eleven MLLMs then judged the responses in three formats: 1–5 scoring, pairwise choice with a tie option, and full ranking of a batch. Their verdicts were compared with independent human annotations. Judges matched human preferences fairly well in pairwise comparison but diverged clearly in scoring and batch ranking, especially on reasoning-heavy tasks. GPT-4V was the strongest judge overall. Every judge showed biases, hallucinations and inconsistent decisions. The work shows that MLLMs are not yet dependable stand-ins for human evaluators, and it supplies annotated preference data usable for reward modelling and DPO.

Key points

  • The benchmark has three steps: collecting image-instruction pairs, gathering responses from GPT-4V, Gemini, LLaVA-1.5-13b, LLaVA-1.6-34b, CogVLM and Qwen-VL-Max, and comparing judge outputs with annotations by six of the authors.
  • Judging was tested with and without vision input on 11 MLLMs, including the GPT-4V, Gemini-Pro-1.0/1.5, LLaVA-1.5/1.6, Qwen-VL and CogVLM families. CogVLM could not perform batch ranking.
  • The paper releases two datasets: MLLM-AS-A-JUDGE-HQ, where responses agree strongly with humans, and MLLM-AS-A-JUDGE-HARD, which holds human-inconsistent and hallucinated cases.
  • The authors identify egocentric, position and length biases plus hallucination. Adding extra CoT reasoning steps and a vision expert system partly reduces these problems.
  • The paper appeared at ICML 2024. Code and data are available at mllm-judge.github.io.

Our summary of the paper, in our own words — not its text. The work belongs to its authors; read it at the links above.

 Institutions

 Fields, topics and concepts

Cite

Cite as Dongping Chen, Ruoxi Chen, Shilin Zhang, Yinuo Liu, Yaochen Wang, Huichi Zhou, Qihui Zhang, Yao Wan, Pan Zhou and Lichao Sun. 2024. MLLM-as-a-Judge: Assessing Multimodal LLM-as-a-Judge with Vision-Language Benchmark. arXiv:2402.04788.

The paper itself, not this page. BibTeX from the library's record of the work. DOI 10.48550/arxiv.2402.04788 · arXiv 2402.04788

@misc{chen2024mllm,
  title = {{MLLM-as-a-Judge: Assessing Multimodal LLM-as-a-Judge with Vision-Language Benchmark}},
  author = {Dongping Chen, Ruoxi Chen, Shilin Zhang, Yinuo Liu, Yaochen Wang, Huichi Zhou, Qihui Zhang, Yao Wan, Pan Zhou and Lichao Sun},
  year = {2024},
  doi = {10.48550/arxiv.2402.04788},
  eprint = {2402.04788},
  archivePrefix = {arXiv},
  url = {https://doi.org/10.48550/arxiv.2402.04788}
}

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