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Mask Propagate

Mask Propagate · screenshot coming soon

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What this node does

Mask Propagate solves the motion between frames of your video and warps a single reference mask to follow it. You give it a first-frame mask image; on ▶ Run it tracks feature points frame to frame, fits a motion model, and re-projects the mask so it sticks to the moving subject or region — outputting a mask video for the full clip. It needs two inputs: the source video (COMFYTV_VIDEO) and a mask image (COMFYTV_IMAGE) that matches the frame at t_ref. If no mask is wired in, it raises “Mask Propagate needs a first-frame mask image.” The output is a COMFYTV_VIDEO mask. Bridge to native ComfyUI nodes via ComfyTV/Bridge — see https://github.com/jtydhr88/ComfyTV/blob/main/docs/bridges.md.

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When to use it

  • You have a clean mask for one frame (from Split Part’s SAM output, Roto Mask, etc.) and want it across the whole shot
  • Following a rigid or near-rigid subject that translates, scales, rotates, or skews
  • Turning a still cutout into a moving matte without rotoscoping every frame

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Parameters

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model

The motion model fitted between frames. Options: translation, similarity, perspective. Default similarity. translation handles pure sliding; similarity adds rotation and scale; perspective adds skew/tilt for planar surfaces. Use the simplest model that matches the motion.

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t_ref

The timestamp (seconds) of the frame your reference mask corresponds to. Range 0–3600, step 0.05, default 0. Set this to the time of the frame you masked.

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max_points

Maximum number of feature points used to solve the motion. Range 4–64, default 24. More points can be more robust but slower.

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invert

Invert the propagated mask. Boolean, default off.

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Inputs and outputs

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Tips

  • The reference mask must line up with the frame at t_ref — a mismatch makes the propagation drift from the start.
  • Split Part’s SAM mask output is a natural source for the first-frame mask.
  • Propagation assumes a mostly consistent transform; heavy deformation, occlusion, or motion blur can cause slippage.
  • Split Part — produces a per-frame SAM mask to seed this node
  • Roto Mask — draw the first-frame mask by hand
  • Motion Track — solve motion as transform data (for pinning/compositing)