Papers with PAC-S
An Examination of the Robustness of Reference-Free Image Captioning Evaluation Metrics (2024.findings-eacl)
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| Challenge: | Recent studies have proposed reference-free evaluations of image captions . however, these approaches are restrictive and favor captions with similar vocabulary but different meanings. |
| Approach: | They propose to use reference-free metrics to evaluate image captions . they propose to combine lexical overlap and semantics to identify fine-grained errors . |
| Outcome: | The proposed metrics struggle to identify fine-grained errors, the authors show . CLIPScore, UMIC, and PAC-S are sensitive to variations in image-relevant objects mentioned in the caption . |
Do Image–Text Metrics Respect Semantic Invariances? (2026.findings-acl)
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Amit Agarwal, Hitesh Laxmichand Patel, Meizhu Liu, Jyotika Singh, Karan Dua, Hansa Meghwani, Matthew Rowe, M. Avendi, Yassi Abbasi, Tao Sheng, Sujith Ravi, Dan Roth
| Challenge: | Reference-free image–to–text evaluators are now standard for scoring image–caption alignment, yet it is unclear whether they respect semantic invariances. |
| Approach: | They propose an invariance probe on five popular evaluators under semantics-preserving perturbations along three axes: spatial edits, object changes, and socio-linguistic framing. |
| Outcome: | The proposed invariance probe shows that spatial edits and simple phrasing changes shift scores by ()6% on average and cause ranking flips in up to (),37% of cases. |