Demystifying the Visual Quality Paradox in Multimodal Large Language Models

Fuente: arXiv
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Auteurs principaux: Xing, Shuo, Guo, Lanqing, Hua, Hongyuan, Lee, Seoyoung, Li, Peiran, Wang, Yufei, Wang, Zhangyang, Tu, Zhengzhong
Format: Preprint
Publié: 2025
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author Xing, Shuo
Guo, Lanqing
Hua, Hongyuan
Lee, Seoyoung
Li, Peiran
Wang, Yufei
Wang, Zhangyang
Tu, Zhengzhong
author_facet Xing, Shuo
Guo, Lanqing
Hua, Hongyuan
Lee, Seoyoung
Li, Peiran
Wang, Yufei
Wang, Zhangyang
Tu, Zhengzhong
contents Recent Multimodal Large Language Models (MLLMs) excel on benchmark vision-language tasks, yet little is known about how input visual quality shapes their responses. Does higher perceptual quality of images already translate to better MLLM understanding? We conduct the first systematic study spanning leading MLLMs and a suite of vision-language benchmarks, applying controlled degradations and stylistic shifts to each image. Surprisingly, we uncover a visual-quality paradox: model, task, and even individual-instance performance can improve when images deviate from human-perceived fidelity. Off-the-shelf restoration pipelines fail to reconcile these idiosyncratic preferences. To close the gap, we introduce Visual-Quality Test-Time Tuning (VQ-TTT)-a lightweight adaptation module that: (1) inserts a learnable, low-rank kernel before the frozen vision encoder to modulate frequency content; and (2) fine-tunes only shallow vision-encoder layers via LoRA. VQ-TTT dynamically adjusts each input image in a single forward pass, aligning it with task-specific model preferences. Across the evaluated MLLMs and all datasets, VQ-TTT lifts significant average accuracy, with no external models, cached features, or extra training data. These findings redefine ``better'' visual inputs for MLLMs and highlight the need for adaptive, rather than universally ``clean'', imagery, in the new era of AI being the main data customer.
format Preprint
id arxiv_https___arxiv_org_abs_2506_15645
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Demystifying the Visual Quality Paradox in Multimodal Large Language Models
Xing, Shuo
Guo, Lanqing
Hua, Hongyuan
Lee, Seoyoung
Li, Peiran
Wang, Yufei
Wang, Zhangyang
Tu, Zhengzhong
Computer Vision and Pattern Recognition
Artificial Intelligence
Recent Multimodal Large Language Models (MLLMs) excel on benchmark vision-language tasks, yet little is known about how input visual quality shapes their responses. Does higher perceptual quality of images already translate to better MLLM understanding? We conduct the first systematic study spanning leading MLLMs and a suite of vision-language benchmarks, applying controlled degradations and stylistic shifts to each image. Surprisingly, we uncover a visual-quality paradox: model, task, and even individual-instance performance can improve when images deviate from human-perceived fidelity. Off-the-shelf restoration pipelines fail to reconcile these idiosyncratic preferences. To close the gap, we introduce Visual-Quality Test-Time Tuning (VQ-TTT)-a lightweight adaptation module that: (1) inserts a learnable, low-rank kernel before the frozen vision encoder to modulate frequency content; and (2) fine-tunes only shallow vision-encoder layers via LoRA. VQ-TTT dynamically adjusts each input image in a single forward pass, aligning it with task-specific model preferences. Across the evaluated MLLMs and all datasets, VQ-TTT lifts significant average accuracy, with no external models, cached features, or extra training data. These findings redefine ``better'' visual inputs for MLLMs and highlight the need for adaptive, rather than universally ``clean'', imagery, in the new era of AI being the main data customer.
title Demystifying the Visual Quality Paradox in Multimodal Large Language Models
topic Computer Vision and Pattern Recognition
Artificial Intelligence
url https://arxiv.org/abs/2506.15645