Rethinking Token Reduction for Large Vision-Language Models

Large Vision-Language Models (LVLMs) excel in visual understanding and reasoning, but the excessive visual tokens lead to high inference costs. Although recent token reduction methods mitigate this issue, they mainly target single-turn Visual Question Answering (VQA), leaving the more practical multi-turn VQA (MT-VQA) scenario largely unexplored. MT-VQA introduces additional challenges, as subsequent questions are unknown beforehand and may refer to arbitrary image regions, making existing reduction strategies ineffective. Specifically, current approaches fall into two categories: prompt-dependent methods, which bias toward the initial text prompt and discard information useful for subsequent turns; prompt-agnostic ones, which, though technically applicable to multi-turn settings, rely on heuristic reduction metrics such as attention scores, leading to suboptimal performance. In this paper, we propose a learning-based prompt-agnostic method, termed MetaCompress, overcoming the limitations of heuristic designs. We begin by formulating token reduction as a learnable compression mapping, unifying existing formats such as pruning and merging into a single learning objective. Upon this formulation, we introduce a data-efficient training paradigm capable of learning optimal compression mappings with limited computational costs. Extensive experiments on MT-VQA benchmarks and across multiple LVLM architectures demonstrate that MetaCompress achieves superior efficiency-accuracy trade-offs while maintaining strong generalization across dialogue turns. Our code is available at https://github.com/MArSha1147/MetaCompress.

Jailbreaking Prompt Attack: A Controllable Adversarial Attack against Diffusion Models

The fast advance of the image generation community has attracted attention worldwide. The safety issue needs to be further scrutinized and studied. There have been a few works around this area mostly achieving a post-processing design, model-specific, or yielding suboptimal image quality generation. Despite that, in this article, we discover a black-box attack method that enjoys three merits. It enables (i)-attacks both directed and semantic-driven that theoretically and practically pose a hazard to this vast user community, (ii)-surprisingly surpasses the white-box attack in a black-box manner and (iii)-without requiring any post-processing effort. Core to our approach is inspired by the concept guidance intriguing property of Classifier-Free guidance (CFG) in T2I models, and we discover that conducting frustratingly simple guidance in the CLIP embedding space, coupled with the semantic loss and an additionally sensitive word list works very well. Moreover, our results expose and highlight the vulnerabilities in existing defense mechanisms.