From Benchmarks to Real-World Use: Evaluating the Robustness of Vision-Language Models for Chart Understanding

Awal Ahmed Fime, Mohammed Saidul Islam, Md Tahmid Rahman Laskar, Md Zarif Hossain, Ridwan Mahbub, Mir Tafseer Nayeem, Mizanur Rahman, Ahmed Imteaj, Enamul Hoque Prince


Abstract
Recent advances in large Vision-Language Models (VLMs) have led to impressive performance on chart understanding tasks. However, existing evaluations are largely limited to clean, canonical charts and do not adequately measure robustness under realistic conditions. To address this gap, we introduce ROBUSTCHART360, a comprehensive benchmark for evaluating chart understanding robustness under realistic real-world variations. ROBUSTCHART360 spans six robustness dimensions covering textual and cross-modal interference, rendering and display degradation, accessibility-oriented transformations, and visual style variation. Using this benchmark, we conduct a large-scale evaluation of 14 proprietary and open-source VLMs across 2,505 chart instances and multiple robustness conditions designed to simulate practical deployment scenarios. Our analysis on 35,070 model responses reveals that current VLMs are highly sensitive to seemingly minor variations such as low-resolution rendering, and mobile layouts, with performance dropping by as much as 33.9% under certain conditions, such as modality gap. We further find that models often over-rely on textual priors when visual and textual signals conflict, indicating weak visual grounding despite strong performance on standard benchmarks. Our findings highlight a substantial gap between benchmark accuracy and real-world robustness, motivating the development of more reliable and visually grounded multimodal systems for chart understanding. We will release our code and dataset at <redacted>.
Anthology ID:
2026.emnlp-industry.165
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing: Industry Track
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Pepa Atanasova, Gholamreza Haffari, Minghan Wang
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
2794–2814
Language:
URL:
https://aclanthology.org/2026.emnlp-industry.165/
DOI:
Bibkey:
Cite (ACL):
Awal Ahmed Fime, Mohammed Saidul Islam, Md Tahmid Rahman Laskar, Md Zarif Hossain, Ridwan Mahbub, Mir Tafseer Nayeem, Mizanur Rahman, Ahmed Imteaj, and Enamul Hoque Prince. 2026. From Benchmarks to Real-World Use: Evaluating the Robustness of Vision-Language Models for Chart Understanding. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing: Industry Track, pages 2794–2814, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
From Benchmarks to Real-World Use: Evaluating the Robustness of Vision-Language Models for Chart Understanding (Fime et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-industry.165.pdf