Vision Transformers (ViTs) have emerged as powerful models in the field of computer vision, delivering superior performance across various vision tasks. However, the high computational complexity poses a significant barrier to their practical applications in real-world scenarios. Motivated by the fact that not all tokens contribute equally to the final predictions and fewer tokens bring less computational cost, reducing redundant tokens has become a prevailing paradigm for accelerating vision transformers. However, we argue that it is not optimal to either only reduce inattentive redundancy by token pruning, or only reduce duplicative redundancy by token merging. To this end, in this paper we propose a novel acceleration framework, namely token Pruning & Pooling Transformers (PPT), to adaptively tackle these two types of redundancy in different layers. By heuristically integrating both token pruning and token pooling techniques in ViTs without additional trainable parameters, PPT effectively reduces the model complexity while maintaining its predictive accuracy. For example, PPT reduces over 37% FLOPs and improves the throughput by over 45% for DeiT-S without any accuracy drop on the ImageNet dataset.

通过在视觉Transformer模型中集成令牌剪枝和令牌汇聚技术，我们提出了一种名为令牌剪枝和汇聚Transformer（PPT）的新型加速框架，通过启发式方法自适应地应对两种不同层次的冗余，有效降低模型复杂性同时保持其预测准确性。例如，PPT在ImageNet数据集上使DeiT-S的FLOPs降低了37%，吞吐量提高了45%以上，而没有准确性下降。

PPT：高效视觉Transformer的令牌修剪和池化