EpiCurveBench: Evaluating VLMs on Epidemic Curve Digitization

Thomas Berkane, Maimuna S. Majumder


Abstract
Chart-to-data extraction with vision-language models (VLMs) is increasingly evaluated on benchmarks that show diminishing headroom (frontier VLMs exceed 89% on ChartQA) and with metrics that treat extracted points as unordered key-value pairs, ignoring the temporal structure of time series and penalizing small alignment shifts as catastrophic failures. We address both gaps with EpiCurveBench, a benchmark of 1,000 epidemic curve images curated from real-world public-health sources, and EpiCurveSimilarity (ECS), an evaluation metric that aligns predicted and ground-truth series via dynamic programming, tolerating local temporal shifts and gaps while penalizing them proportionally. Evaluating nine methods—three frontier closed VLMs, four open VLM, and two specialized chart-extraction systems—we find the strongest model reaches only 52.3% ECS, and that ECS spreads the four general-purpose VLMs over a 25-point range where key-value metrics (RMS, SCRM) compress them into a 5-point band. We further validate ECS against four downstream epidemiological summary statistics, finding that higher ECS predicts smaller errors in total counts, peak timing, and peak magnitude, and higher growth-rate fidelity; across all four, ECS correlates 1.5–3.6× more strongly than Dynamic Time Warping, which lacks a gap penalty and therefore cannot distinguish a truncated prediction from a temporally faithful one. EpiCurveBench targets a high-impact public-health application—unlocking decades of outbreak data trapped in published figures—but the benchmark and metric apply directly to any structured time-series chart-extraction setting.
Anthology ID:
2026.emnlp-main.1409
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
32188–32201
Language:
URL:
https://aclanthology.org/2026.emnlp-main.1409/
DOI:
Bibkey:
Cite (ACL):
Thomas Berkane and Maimuna S. Majumder. 2026. EpiCurveBench: Evaluating VLMs on Epidemic Curve Digitization. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 32188–32201, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
EpiCurveBench: Evaluating VLMs on Epidemic Curve Digitization (Berkane & Majumder, EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.1409.pdf