Junyan Zhang


2025

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VLA-Mark: A cross modal watermark for large vision-language alignment models
Shuliang Liu | Zheng Qi | Jesse Jiaxi Xu | Yibo Yan | Junyan Zhang | He Geng | Aiwei Liu | Peijie Jiang | Jia Liu | Yik-Cheung Tam | Xuming Hu
Proceedings of the 2025 Conference on Empirical Methods in Natural Language Processing

Vision-language models demand watermarking solutions that protect intellectual property without compromising multimodal coherence. Existing text watermarking methods disrupt visual-textual alignment through biased token selection and static strategies, leaving semantic-critical concepts vulnerable. We propose VLA-Mark, a vision-aligned framework that embeds detectable watermarks while preserving semantic fidelity through cross-modal coordination. Our approach integrates multiscale visual-textual alignment metrics, combining localized patch affinity, global semantic coherence, and contextual attention patterns, to guide watermark injection without model retraining. An entropy-sensitive mechanism dynamically balances watermark strength and semantic preservation, prioritizing visual grounding during low-uncertainty generation phases. Experiments show 7.4% lower PPL and 26.6% higher BLEU than conventional methods, with near-perfect detection (98.8% AUC). The framework demonstrates 96.1% attack resilience against attacks such as paraphrasing and synonym substitution, while maintaining text-visual consistency, establishing new standards for quality-preserving multimodal watermarking.