PostAlign: Multimodal Grounding as a Corrective Lens for MLLMs

Fuente: arXiv
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Autores principales: Wu, Yixuan, Zhang, Yang, Wu, Jian, Torr, Philip, Gu, Jindong
Formato: Preprint
Publicado: 2025
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author Wu, Yixuan
Zhang, Yang
Wu, Jian
Torr, Philip
Gu, Jindong
author_facet Wu, Yixuan
Zhang, Yang
Wu, Jian
Torr, Philip
Gu, Jindong
contents Multimodal Large Language Models (MLLMs) excel in vision-language tasks, such as image captioning and visual question answering. However, they often suffer from over-reliance on spurious correlations, primarily due to linguistic priors that distract the model from leveraging actual visual information. To address these issues, we introduce MMGrounded-PostAlign, a post-multimodal alignment framework designed to enhance the visual understanding capabilities and mitigate the hallucinations of MLLMs. Our framework incorporates a multimodal grounding module for both visual grounding, which identifies the referred object in the image, and textual grounding, which generates the rationale for the final answer, ensuring that outputs are anchored in both visual and textual evidence. To mitigate the hallucinations, we introduce a negative rejection mechanism in the visual grounding module to distinguish grounded entities from non-existent objects influenced by linguistic biases. On the textual grounding side, we propose a selective reasoning mechanism that adjusts the model's reasoning strategy based on query complexity. Extensive evaluations are conducted on benchmarks such as POPE, HaloQuest, VQAv2, MME, and MMBench showing significant improvements in fine-grained visual understanding and hallucination suppression.
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spellingShingle PostAlign: Multimodal Grounding as a Corrective Lens for MLLMs
Wu, Yixuan
Zhang, Yang
Wu, Jian
Torr, Philip
Gu, Jindong
Computer Vision and Pattern Recognition
Multimodal Large Language Models (MLLMs) excel in vision-language tasks, such as image captioning and visual question answering. However, they often suffer from over-reliance on spurious correlations, primarily due to linguistic priors that distract the model from leveraging actual visual information. To address these issues, we introduce MMGrounded-PostAlign, a post-multimodal alignment framework designed to enhance the visual understanding capabilities and mitigate the hallucinations of MLLMs. Our framework incorporates a multimodal grounding module for both visual grounding, which identifies the referred object in the image, and textual grounding, which generates the rationale for the final answer, ensuring that outputs are anchored in both visual and textual evidence. To mitigate the hallucinations, we introduce a negative rejection mechanism in the visual grounding module to distinguish grounded entities from non-existent objects influenced by linguistic biases. On the textual grounding side, we propose a selective reasoning mechanism that adjusts the model's reasoning strategy based on query complexity. Extensive evaluations are conducted on benchmarks such as POPE, HaloQuest, VQAv2, MME, and MMBench showing significant improvements in fine-grained visual understanding and hallucination suppression.
title PostAlign: Multimodal Grounding as a Corrective Lens for MLLMs
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2506.17901