Mask node

A Mask node marks part of a picture or a clip. On its own it shows nothing useful — it exists to tell another node which area to work on.

You start by describing the thing in words, or marking it once on the frame. The node works out its edges and follows it across every frame of a clip.

On a clip, you can also fix what it got wrong frame by frame. Press Edit frames, then paint the matte back in where it missed or erase where it grabbed too much. You only touch the frames that need it.

Edit frames is for clips only. On a single picture there is nothing to step through, so the button does not appear.

1. Wire your picture or clip into the node’s init input.
2. Open the Inspector and type what you want picked out, like "the person".
3. Or press Mark subject and click the thing on the frame.
4. Press Generate mask.
5. On a clip, press Edit frames and paint or erase any frame the mask got wrong.
6. Wire the result into the mask input of the node doing the change.

Plain nouns work better than descriptions. "The red car" finds a car; "the vehicle in the middle distance on the left" often finds nothing.