🤖 AI Summary
To address the high computational and memory overhead of Vision Transformers—hindering their deployment in resource-constrained scenarios—this paper proposes a hierarchical “prune-merge” token compression framework. Our method introduces three key innovations: (1) a gradient-weighted attention scoring mechanism that dynamically evaluates token importance during training; (2) learnable merge/reconstruction matrices coupled with residual connections, enabling structured reconstruction of pruned tokens; and (3) end-to-end joint optimization guided by global gradient sensitivity, automatically discovering optimal compression architectures. Evaluated on ImageNet-1K, our approach accelerates DeiT-Small inference by 1.64× with only a 0.2% top-1 accuracy drop. On ADE20K semantic segmentation, it significantly outperforms existing token compression methods. The framework achieves efficient yet accurate vision modeling without architectural modification, offering a principled pathway toward lightweight ViT deployment.
📝 Abstract
Token compression is essential for reducing the computational and memory requirements of transformer models, enabling their deployment in resource-constrained environments. In this work, we propose an efficient and hardware-compatible token compression method called Prune and Merge. Our approach integrates token pruning and merging operations within transformer models to achieve layer-wise token compression. By introducing trainable merge and reconstruct matrices and utilizing shortcut connections, we efficiently merge tokens while preserving important information and enabling the restoration of pruned tokens. Additionally, we introduce a novel gradient-weighted attention scoring mechanism that computes token importance scores during the training phase, eliminating the need for separate computations during inference and enhancing compression efficiency. We also leverage gradient information to capture the global impact of tokens and automatically identify optimal compression structures. Extensive experiments on the ImageNet-1k and ADE20K datasets validate the effectiveness of our approach, achieving significant speed-ups with minimal accuracy degradation compared to state-of-the-art methods. For instance, on DeiT-Small, we achieve a 1.64$ imes$ speed-up with only a 0.2% drop in accuracy on ImageNet-1k. Moreover, by compressing segmenter models and comparing with existing methods, we demonstrate the superior performance of our approach in terms of efficiency and effectiveness. Code and models have been made available at https://github.com/NUST-Machine-Intelligence-Laboratory/prune_and_merge.