发现图像令牌是幻觉主因,零训练移除特定令牌可大幅降低模型幻觉。
Hallucinatory Image Tokens: A Training-free EAZY Approach on Detecting and Mitigating Object Hallucinations in LVLMs
- 从图像令牌角度切入,识别高注意力值的幻觉源令牌。
- 仅移除1.5%的令牌即有效抑制幻觉,跨模型数据集稳定生效。
- 无需训练即可检测与缓解幻觉,适配多种视觉语言模型。
尽管大型视觉语言模型(LVLMs)潜力巨大,但仍存在对象幻觉问题,即生成内容错误引入实际不存在的对象。现有研究多聚焦于语言模型本身,本文转而关注图像输入源,发现少数高注意力图像令牌(仅占所有令牌的1.5%)是幻觉的主要驱动因素。通过移除这些幻觉令牌,可有效缓解幻觉问题,且该现象在不同模型和数据集上均成立。基于此,我们提出EAZY方法——一种无需训练的自动识别并消除幻觉图像令牌的技术。利用EAZY实现无监督幻觉检测,较先前方法提升15%;同时在保持模型性能前提下,有效缓解幻觉,并可无缝适配多种LVLM架构。
原文摘要 · Abstract (English)
Despite their remarkable potential, Large Vision-Language Models (LVLMs) still face challenges with object hallucination, a problem where their generated outputs mistakenly incorporate objects that do not actually exist. Although most works focus on addressing this issue within the language-model backbone, our work shifts the focus to the image input source, investigating how specific image tokens contribute to hallucinations. Our analysis reveals a striking finding: a small subset of image tokens with high attention scores are the primary drivers of object hallucination. By removing these hallucinatory image tokens (only 1.5% of all image tokens), the issue can be effectively mitigated. This finding holds consistently across different models and datasets. Building on this insight, we introduce EAZY, a novel, training-free method that automatically identifies and Eliminates hAllucinations by Zeroing out hallucinatorY image tokens. We utilize EAZY for unsupervised object hallucination detection, achieving 15% improvement compared to previous methods. Additionally, EAZY demonstrates remarkable effectiveness in mitigating hallucinations while preserving model utility and seamlessly adapting to various LVLM architectures.
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