Motion brush
Motion brush is the AI video tool that lets a user paint motion onto specific regions of an image — telling the model where motion should happen and which direction it should go — instead of relying purely on text prompts.
Pioneered by Runway in 2024 and widely adopted by 2026, motion brush gives directors precise control over which parts of a generated clip move. Paint over a character's hair and pick a direction → the hair flows that way. Paint over a candle flame and pick "up" → it flickers. Compared to text-only motion direction ("the character's hair flows in the wind"), motion brush is dramatically more controllable. Used heavily in production for ads, character work, and any clip where natural motion was previously hard to control.
When to use motion brush
- Image-to-video with precise motion control.
- Character work where motion matters.
- Ads where the brief is exact.
Common mistakes
- Painting motion that's physically implausible — clips look broken.
- Skipping motion brush on shots that needed it — using only text instead.
FAQ
What is motion brush?
Motion brush is the AI video tool that lets a user paint motion onto specific regions of an image — telling the model where motion should happen and which direction it should go — instead of relying purely on text prompts.
When should I use motion brush?
Image-to-video with precise motion control. Character work where motion matters. Ads where the brief is exact.
What are the most common mistakes with motion brush?
Painting motion that's physically implausible — clips look broken. Skipping motion brush on shots that needed it — using only text instead.
Related terms
- Diffusion model — A diffusion model is a generative neural network that creates images, video, or audio by iteratively denoising random noise toward a learned target distribution.
- ControlNet — ControlNet is a neural-network architecture that conditions a diffusion image model on extra spatial inputs — edges, depth, pose, segmentation — for precise control over output structure.
Last updated: 2026-06-01. Raw markdown: https://promtable.com/glossary/motion-brush.md.