DECENT: Distribution-aware Prototypical Calibration with Fine-grained Voting for VLM Misclassification Detection

Yijun Gong, Bohan Yang, Zhi Zhang, Yupeng Qin, Wenpeng Xing, Changting Lin, Meng Han, Ziyue Qiao, Xiao Luo


Abstract
This paper studies the problem of misclassification detection for vision-language models (VLMs), which aims to identify samples wrongly assigned by the pre-trained VLM. Previous works usually focus on exploring the latent space and measuring pairwise similarity scores for confidence estimation. However, these similarity scores can be biased for boundary points with different fine-grained features. To address this issue, this paper proposes an approach named Distribution-aware Prototypical Calibration with Fine-grained Voting (DECENT). The core idea of DECENT is to utilize probabilistic distributions to characterize both the semantics of the test image and its corresponding class prototype. Specifically, we first conduct clustering within each class in the latent space to construct a distribution of fine grained prototypes. More importantly, multiple augmented views of the test image are considered as samples from its underlying semantic distribution. Then, we measure the distribution distance between the image’s underlying semantic distribution and its neighboring fine grained prototype distributions, which is aggregated via fine-grained voting into a distributional score. This score can be fused with the VLM’s semantic alignment score to significantly enhance misclassification detection sensitivity, or to improve overall classification robustness. Extensive experiments on benchmark datasets validate the dual effectiveness of the proposed DECENT.
Anthology ID:
2026.emnlp-main.1665
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:
37858–37873
Language:
URL:
https://aclanthology.org/2026.emnlp-main.1665/
DOI:
Bibkey:
Cite (ACL):
Yijun Gong, Bohan Yang, Zhi Zhang, Yupeng Qin, Wenpeng Xing, Changting Lin, Meng Han, Ziyue Qiao, and Xiao Luo. 2026. DECENT: Distribution-aware Prototypical Calibration with Fine-grained Voting for VLM Misclassification Detection. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 37858–37873, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
DECENT: Distribution-aware Prototypical Calibration with Fine-grained Voting for VLM Misclassification Detection (Gong et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.1665.pdf