LVLM_CSP: Accelerating Large Vision Language Models via Clustering, Scattering, and Pruning for Reasoning Segmentation
Hanning Chen, Yang Ni, Wenjun Huang, Hyunwoo Oh, Yezi Liu, Tamoghno Das, Mohsen Imani
TL;DR
This work tackles the high computational cost of large vision-language models (LVLMs) in reasoning-based segmentation by introducing LVLM_CSP, a training-free three-stage framework that clusters, scatters, and prunes image tokens. By performing coarse-grained reasoning on a small representative token set, then reactivating all tokens for fine-grained analysis and finally aggressively pruning tokens based on the [SEG] token attention, LVLM_CSP dramatically reduces average tokens per MHSA layer and FLOPs. Empirical results on multiple datasets and LVLM backbones show 65% token and TFLOPs reduction with virtually no accuracy loss, increasing to 70% with only a 1% drop after fine-tuning, and speedups ranging from 2x to 4x. The approach outperforms prior LVLM token-pruning methods in reasoning-based segmentation by maintaining high mIoU while enabling substantial efficiency gains, highlighting the value of a coarse-to-fine, segmentation-focused pruning strategy.
Abstract
Large Vision Language Models (LVLMs) have been widely adopted to guide vision foundation models in performing reasoning segmentation tasks, achieving impressive performance. However, the substantial computational overhead associated with LVLMs presents a new challenge. The primary source of this computational cost arises from processing hundreds of image tokens. Therefore, an effective strategy to mitigate such overhead is to reduce the number of image tokens, a process known as image token pruning. Previous studies on image token pruning for LVLMs have primarily focused on high level visual understanding tasks, such as visual question answering and image captioning. In contrast, guiding vision foundation models to generate accurate visual masks based on textual queries demands precise semantic and spatial reasoning capabilities. Consequently, pruning methods must carefully control individual image tokens throughout the LVLM reasoning process. Our empirical analysis reveals that existing methods struggle to adequately balance reductions in computational overhead with the necessity to maintain high segmentation accuracy. In this work, we propose LVLM_CSP, a novel training free visual token pruning method specifically designed for LVLM based reasoning segmentation tasks. LVLM_CSP consists of three stages: clustering, scattering, and pruning. Initially, the LVLM performs coarse-grained visual reasoning using a subset of selected image tokens. Next, fine grained reasoning is conducted, and finally, most visual tokens are pruned in the last stage. Extensive experiments demonstrate that LVLM_CSP achieves a 65% reduction in image token inference FLOPs with virtually no accuracy degradation, and a 70% reduction with only a minor 1% drop in accuracy on the 7B LVLM.