| Title: |
Revisiting data auditing in large vision-language models |
| Authors: |
Zhu, Hongyu; Liang, Sichu; Wang, Wenwen; Li, Boheng; Yuan, Tongxin; Li, Fangqi; Wang, Hanyi; Wang, Shi-Lin; Zhang, Zhuosheng |
| Contributors: |
College of Computing and Data Science; 33rd ACM International Conference on Multimedia (MM ’25) |
| Publisher Information: |
ACM |
| Publication Year: |
2025 |
| Collection: |
DR-NTU (Digital Repository at Nanyang Technological University, Singapore) |
| Subject Terms: |
Computer and Information Science; Data transparency; Vision-language models |
| Description: |
With the surge of large language models (LLMs), Large Vision-Language Models (VLMs)-which integrate vision encoders with LLMs for accurate visual grounding-have shown great potential in tasks like generalist agents and robotic control. However, VLMs are typically trained on massive web-scraped images, raising concerns over copyright infringement and privacy violations, and making data auditing increasingly urgent. Membership inference (MI), which determines whether a sample was used in training, has emerged as a key auditing technique, with promising results on open-source VLMs like LLaVA (AUC > 80%). In this work, we revisit these advances and uncover a critical issue: current MI benchmarks suffer from distribution shifts between member and non-member images, introducing shortcut cues that inflate MI performance. We further analyze the nature of these shifts and propose a principled metric based on optimal transport to quantify the distribution discrepancy. To evaluate MI in realistic settings, we construct new benchmarks with i.i.d. member and non-member images. Existing MI methods fail under these unbiased conditions, performing only marginally better than chance. Further, we explore the theoretical upper bound of MI by probing the Bayes Optimality within the VLM's embedding space and find the irreducible error rate remains high. Despite this pessimistic outlook, we analyze why MI for VLMs is particularly challenging and identify three practical scenarios-fine-tuning, access to ground-truth texts, and set-based inference-where auditing becomes feasible. Our study presents a systematic view of the limits and opportunities of MI for VLMs, providing guidance for future efforts in trustworthy data auditing. Code and data will be available at https://github.com/GradOpt/Revisiting-VLM-MIA\faGithub. ; Published version ; With the surge of large language models (LLMs), Large Vision-Language Models (VLMs)-which integrate vision encoders with LLMs for accurate visual grounding-have shown great potential in tasks ... |
| Document Type: |
conference object |
| File Description: |
application/pdf |
| Language: |
English |
| Relation: |
https://hdl.handle.net/10356/202558; 11337; 11346 |
| DOI: |
10.1145/3746027.3755002 |
| Availability: |
https://hdl.handle.net/10356/202558; https://doi.org/10.1145/3746027.3755002 |
| Rights: |
© 2025 Copyright held by the owner/author(s). Publication rights licensed to ACM. All rights reserved. This article may be downloaded for personal use only. Any other use requires prior permission of the copyright holder. The Version of Record is available online at https://doi.org/10.1145/3746027.3755002. |
| Accession Number: |
edsbas.89A4E63C |
| Database: |
BASE |