PyramidDrop: Accelerating Your Large Vision-Language Models via Pyramid
  Visual Redundancy Reduction
Authors: name: Long Xing, name: Qidong Huang, name: Xiaoyi Dong, name: Jiajie Lu, name: Pan Zhang, name: Yuhang Zang, name: Yuhang Cao, name: Conghui He, name: Jiaqi Wang, name: Feng Wu, name: Dahua Lin

In large vision-language models (LVLMs), images serve as inputs that carry a
wealth of information. As the idiom "A picture is worth a thousand words"
implies, representing a single image in current LVLMs can require hundreds or
even thousands of tokens. This results in significant computational costs,
which grow quadratically as input image resolution increases, thereby severely
impacting the efficiency of both training and inference. Previous approaches
have attempted to reduce the number of image tokens either before or within the
early layers of LVLMs. However, these strategies inevitably result in the loss
of crucial image information, ultimately diminishing model performance. To
address this challenge, we conduct an empirical study revealing that all visual
tokens are necessary for LVLMs in the shallow layers, and token redundancy
progressively increases in the deeper layers of the model. To this end, we
propose PyramidDrop, a visual redundancy reduction strategy for LVLMs to boost
their efficiency in both training and inference with neglectable performance
loss. Specifically, we partition the LVLM into several stages and drop part of
the image tokens at the end of each stage with a pre-defined ratio, creating
pyramid-like visual tokens across model layers. The dropping is based on a
lightweight similarity calculation with a negligible time overhead. Extensive
experiments demonstrate that PyramidDrop can achieve a 40% training time and
55% inference FLOPs acceleration of LLaVA-NeXT with comparable performance.
Besides, the PyramidDrop could also serve as a plug-and-play strategy for
inference acceleration without training, with better performance and lower
inference cost than counterparts. We hope that the insights and approach
introduced by PyramidDrop will inspire future research to further investigate
the role of image tokens in LVLMs.