FOCUS: Internal MLLM Representations for Efficient Fine-Grained Visual Question Answering

Fuente: arXiv
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Main Authors: Zhong, Liangyu, Rosenthal, Fabio, Sicking, Joachim, Hüger, Fabian, Bagdonat, Thorsten, Gottschalk, Hanno, Schwinn, Leo
Format: Preprint
Published: 2025
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author Zhong, Liangyu
Rosenthal, Fabio
Sicking, Joachim
Hüger, Fabian
Bagdonat, Thorsten
Gottschalk, Hanno
Schwinn, Leo
author_facet Zhong, Liangyu
Rosenthal, Fabio
Sicking, Joachim
Hüger, Fabian
Bagdonat, Thorsten
Gottschalk, Hanno
Schwinn, Leo
contents While Multimodal Large Language Models (MLLMs) offer strong perception and reasoning capabilities for image-text input, Visual Question Answering (VQA) focusing on small image details still remains a challenge. Although visual cropping techniques seem promising, recent approaches have several limitations: the need for task-specific fine-tuning, low efficiency due to uninformed exhaustive search, or incompatibility with efficient attention implementations. We address these shortcomings by proposing a training-free visual cropping method, dubbed FOCUS, that leverages MLLM-internal representations to guide the search for the most relevant image region. This is accomplished in four steps: first, we identify the target object(s) in the VQA prompt; second, we compute an object relevance map using the key-value (KV) cache; third, we propose and rank relevant image regions based on the map; and finally, we perform the fine-grained VQA task using the top-ranked region. As a result of this informed search strategy, FOCUS achieves strong performance across four fine-grained VQA datasets and three types of MLLMs. It outperforms three popular visual cropping methods in both accuracy and efficiency, and matches the best-performing baseline, ZoomEye, while requiring 3 - 6.5 x less compute.
format Preprint
id arxiv_https___arxiv_org_abs_2506_21710
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle FOCUS: Internal MLLM Representations for Efficient Fine-Grained Visual Question Answering
Zhong, Liangyu
Rosenthal, Fabio
Sicking, Joachim
Hüger, Fabian
Bagdonat, Thorsten
Gottschalk, Hanno
Schwinn, Leo
Computer Vision and Pattern Recognition
While Multimodal Large Language Models (MLLMs) offer strong perception and reasoning capabilities for image-text input, Visual Question Answering (VQA) focusing on small image details still remains a challenge. Although visual cropping techniques seem promising, recent approaches have several limitations: the need for task-specific fine-tuning, low efficiency due to uninformed exhaustive search, or incompatibility with efficient attention implementations. We address these shortcomings by proposing a training-free visual cropping method, dubbed FOCUS, that leverages MLLM-internal representations to guide the search for the most relevant image region. This is accomplished in four steps: first, we identify the target object(s) in the VQA prompt; second, we compute an object relevance map using the key-value (KV) cache; third, we propose and rank relevant image regions based on the map; and finally, we perform the fine-grained VQA task using the top-ranked region. As a result of this informed search strategy, FOCUS achieves strong performance across four fine-grained VQA datasets and three types of MLLMs. It outperforms three popular visual cropping methods in both accuracy and efficiency, and matches the best-performing baseline, ZoomEye, while requiring 3 - 6.5 x less compute.
title FOCUS: Internal MLLM Representations for Efficient Fine-Grained Visual Question Answering
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2506.21710