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SmolVLM: Visual token compression for small models

简体中文

Local pixel-shuffle compression and projection, not the full decoder or data recipe.

Paper information

Field Details
Paper arXiv 2504.05299
Institution Hugging Face.
First public release 2025-04-07 (arXiv v1)
Author code huggingface/smollm.
Local adapter or method key smolvlm
Local reproduction code src/auto_research/reproductions/smolvlm/

Paper method and evidence

Move neighboring spatial tokens into channels with pixel shuffle, then project into LM space with an MLP. The paper also studies long contexts, image tiling, learned position tokens and data mixtures for 256M/500M/2.2B image/video models.

flowchart LR
  I[Visual feature grid] --> P[Space to depth]
  P --> M[MLP to LM space]
  M --> C[Fewer visual tokens]

Original paper figure

SmolVLM paper figure

The original figure shows the compact visual-language design. From the original paper; copyright remains with the authors.

Core equation

\[ X'_{h,w,:}=\operatorname{Concat}_{0\le i,j<r}X_{rh+i,rw+j,:}, \qquad |X'|=|X|/r^2. \]

Reported results

The paper reports under 1GB inference memory for 256M and better results than roughly 300× larger Idefics-80B; the 2.2B variant is competitive with larger VLMs on image/video tasks. No industrial A/B.

Local reproduction

Mean-pooling linear connector vs r=2 pixel shuffle + projector: test accuracy 46.8%→65.8% (+19.0 points), visual tokens 16→4 (-75%).

auto-research reproduce --paper smolvlm --dataset-dir data --seed 42

Fixed metrics. Real 32×32 clothing images with 2×2 space-to-depth; no high-res tiles, video sampling, 8k/16k context, learned position tokens or SmolLM decoder.