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LookWhen? Fast Video Recognition by Learning When, Where, and What to Compute

Summary

LookWhen is a video recognition framework that uses a selector-extractor mechanism to learn when, where, and what to compute, approximating full-video representations without processing all tokens, achieving a better accuracy-computation trade-off. Experiments show it is 6.7x faster than InternVideo2-B at equal accuracy.

SourcearXiv Computer VisionAuthor: Ali Salamatian, Anthony Fuller, Pritam Sarkar, James R. Green, Leonid Sigal, Evan Shelhamer
LookWhen? Fast Video Recognition by Learning When, Where, and What to Compute
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[2605.06809] LookWhen? Fast Video Recognition by Learning When, Where, and What to Compute

[Submitted on 7 May 2026]

Title:LookWhen? Fast Video Recognition by Learning When, Where, and What to Compute

View a PDF of the paper titled LookWhen? Fast Video Recognition by Learning When, Where, and What to Compute, by Ali Salamatian and Anthony Fuller and Pritam Sarkar and James R. Green and Leonid Sigal and Evan Shelhamer

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Abstract:Transformers dominate video recognition. They split videos into tokens, and processing them has expensive superlinear computational cost. Yet videos are filled with redundancy, so we can question the need for this expense. We introduce LookWhen, a selector-extractor framework that factorizes video recognition into learning when, where, and what to compute. Our shallow selector gets a scaled-down video and quickly scores all tokens across space-time, while our deep extractor gets the top-K selected tokens to approximate full-video representations without actually processing all the tokens. A key challenge is defining effective supervision for selection and extraction. For selection pre-training, we introduce a score on representations that ranks tokens by uniqueness using a simple nearest-neighbor distance. For extraction pre-training, we distill both a video teacher and an image teacher, for which we normalize its frame-wise representations to learn what changes within videos. Through these strategies, our selector-extractor learns general and efficient representations for feature extraction or fine-tuning to a task. Through experiments on Kinetics-400, SSv2, Epic-Kitchens, Diving48, Jester, and Charades, we show that LookWhen achieves a better accuracy-computation trade-off than efficient models and upgraded baselines of similar size. LookWhen Pareto-dominates in accuracy-FLOPs on 9 of 12 cases (6 tasks x 2 settings) and roughly matches on 3. In accuracy-throughput, measuring time in practice, LookWhen is more efficient still at 6.7x faster than InternVideo2-B at equal accuracy.

Subjects:

Computer Vision and Pattern Recognition (cs.CV); Machine Learning (cs.LG)

Cite as: arXiv:2605.06809 [cs.CV]

(or arXiv:2605.06809v1 [cs.CV] for this version)

https://doi.org/10.48550/arXiv.2605.06809

arXiv-issued DOI via DataCite

Submission history

From: Anthony Fuller [view email] [v1] Thu, 7 May 2026 18:08:31 UTC (7,291 KB)

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Key points and analysis

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Key points

  • LookWhen decomposes video recognition into learning when, where, and what to compute.
  • A shallow selector scores all spatiotemporal tokens, while a deep extractor processes only top-K tokens.
  • Pre-training uses uniqueness score for selection and distillation from video/image teachers for extraction.
  • On 6 datasets, LookWhen Pareto-dominates in accuracy-FLOPs on 9 of 12 cases and is significantly more efficient in throughput.

Highlights and analysis are generated automatically and may contain errors. Check the original source.