CROC: Evaluating and Training T2I Metrics with Pseudo- and Human-Labeled Contrastive Robustness Checks

Christoph Leiter, Yuki M. Asano, Margret Keuper, Steffen Eger


Abstract
The assessment of evaluation metrics (meta-evaluation) is crucial for determining the suitability of existing metrics in text-to-image (T2I) generation tasks. Human-based meta-evaluation is costly and time-intensive, and automated alternatives are scarce. We address this gap and propose CROC: a scalable framework for automated Contrastive Robustness Checks that systematically probes and quantifies metric robustness by synthesizing contrastive test cases across a comprehensive taxonomy of image properties. With CROC, we generate a pseudo-labeled dataset (CROCsyn) of over 1 million contrastive prompt–image pairs to enable a fine-grained comparison of evaluation metrics. We also use this dataset to train CROCScore, a new metric that achieves state-of-the-art performance among open-source methods, demonstrating an additional key application of our framework. To complement this dataset, we introduce a human-supervised benchmark (CROChum) targeting especially challenging categories. Our results highlight robustness issues in existing metrics: for example, many fail on prompts involving negation, and all tested open-source metrics fail on at least 24% of cases involving correct identification of body parts.1
Anthology ID:
2026.tacl-1.50
Volume:
Transactions of the Association for Computational Linguistics, Volume 14
Month:
Year:
2026
Address:
Cambridge, MA
Venue:
TACL
SIG:
Publisher:
MIT Press
Note:
Pages:
1119–1139
Language:
URL:
https://aclanthology.org/2026.tacl-1.50/
DOI:
10.1162/tacl.a.699
Bibkey:
Cite (ACL):
Christoph Leiter, Yuki M. Asano, Margret Keuper, and Steffen Eger. 2026. CROC: Evaluating and Training T2I Metrics with Pseudo- and Human-Labeled Contrastive Robustness Checks. Transactions of the Association for Computational Linguistics, 14:1119–1139.
Cite (Informal):
CROC: Evaluating and Training T2I Metrics with Pseudo- and Human-Labeled Contrastive Robustness Checks (Leiter et al., TACL 2026)
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PDF:
https://aclanthology.org/2026.tacl-1.50.pdf