让图像令牌更像单词,提升多模态模型效率与准确性
A More Word-like Image Tokenization for MLLMs

- 将图像分块嵌入聚类为语义连贯的视觉单元,生成类词令牌
- 用更少令牌达到同等甚至更好性能,降低内存与延迟
- 无需改动视觉编码器或语言模型,适合资源受限场景
当前多模态大模型通常固定语言模型,通过视觉投影器将像素映射为连续、高度相关的嵌入序列,但这类表示与语言模型训练时的离散语义令牌差异显著。本文提出解耦视觉令牌化(DiVT),将图像块嵌入聚类为语义一致的视觉单元,使每个令牌对应一个明确视觉概念而非固定网格区域。DiVT可自适应图像复杂度调整令牌数量,在不修改视觉编码器或语言模型的前提下,实现显式的精度-计算权衡。在多个多模态基准测试中,DiVT以显著更少的视觉令牌匹配或超越基线,展现出在有限令牌预算下的鲁棒性,大幅降低内存消耗和推理延迟,使视觉输入更契合语言模型处理逻辑。
原文摘要 · Abstract (English)
Modern multimodal large language models (MLLMs) typically keep the language model fixed and train a visual projector that maps the pixels into a sequence of tokens in its embedding space, so that images can be presented in essentially the same form as text. However, the language model has been optimized to operate on discrete, semantically meaningful tokens, while prevailing visual projectors transform an image into a long stream of continuous and highly correlated embeddings. This causes the visual tokens to behave differently from the word-like units that LLMs are originally trained to understand. We propose a novel Disentangled Visual Tokenization (DiVT) that clusters patch embeddings into coherent semantic units, so each token corresponds to a distinct visual concept instead of a rigid grid cell. DiVT further adapts its token budget to image complexity, providing an explicit accuracy-compute trade-off modifying neither the vision encoder nor the language model. Across diverse multimodal benchmarks, DiVT matches or surpasses baselines with significantly fewer visual tokens, demonstrating robustness under limited token budgets, significantly reducing memory cost and latency while making visual inputs more compatible with LLMs. Our code is available at https://github.com/snuviplab/DiVT.
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