On Large Multimodal Models as Open-World Image Classifiers

Fuente: arXiv
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Main Authors: Conti, Alessandro, Mancini, Massimiliano, Fini, Enrico, Wang, Yiming, Rota, Paolo, Ricci, Elisa
Format: Preprint
Published: 2025
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author Conti, Alessandro
Mancini, Massimiliano
Fini, Enrico
Wang, Yiming
Rota, Paolo
Ricci, Elisa
author_facet Conti, Alessandro
Mancini, Massimiliano
Fini, Enrico
Wang, Yiming
Rota, Paolo
Ricci, Elisa
contents Traditional image classification requires a predefined list of semantic categories. In contrast, Large Multimodal Models (LMMs) can sidestep this requirement by classifying images directly using natural language (e.g., answering the prompt "What is the main object in the image?"). Despite this remarkable capability, most existing studies on LMM classification performance are surprisingly limited in scope, often assuming a closed-world setting with a predefined set of categories. In this work, we address this gap by thoroughly evaluating LMM classification performance in a truly open-world setting. We first formalize the task and introduce an evaluation protocol, defining various metrics to assess the alignment between predicted and ground truth classes. We then evaluate 13 models across 10 benchmarks, encompassing prototypical, non-prototypical, fine-grained, and very fine-grained classes, demonstrating the challenges LMMs face in this task. Further analyses based on the proposed metrics reveal the types of errors LMMs make, highlighting challenges related to granularity and fine-grained capabilities, showing how tailored prompting and reasoning can alleviate them.
format Preprint
id arxiv_https___arxiv_org_abs_2503_21851
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle On Large Multimodal Models as Open-World Image Classifiers
Conti, Alessandro
Mancini, Massimiliano
Fini, Enrico
Wang, Yiming
Rota, Paolo
Ricci, Elisa
Computer Vision and Pattern Recognition
Traditional image classification requires a predefined list of semantic categories. In contrast, Large Multimodal Models (LMMs) can sidestep this requirement by classifying images directly using natural language (e.g., answering the prompt "What is the main object in the image?"). Despite this remarkable capability, most existing studies on LMM classification performance are surprisingly limited in scope, often assuming a closed-world setting with a predefined set of categories. In this work, we address this gap by thoroughly evaluating LMM classification performance in a truly open-world setting. We first formalize the task and introduce an evaluation protocol, defining various metrics to assess the alignment between predicted and ground truth classes. We then evaluate 13 models across 10 benchmarks, encompassing prototypical, non-prototypical, fine-grained, and very fine-grained classes, demonstrating the challenges LMMs face in this task. Further analyses based on the proposed metrics reveal the types of errors LMMs make, highlighting challenges related to granularity and fine-grained capabilities, showing how tailored prompting and reasoning can alleviate them.
title On Large Multimodal Models as Open-World Image Classifiers
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2503.21851