Garbage Matte to Cut “hole” in Video

[Thaxter Clavemarlton]

[Bret Williams] “If it’s a white wall, you can probably key out the wall with a simple key, but “key out brighter” instead of darker. “

That is surely the best way to go in this case.

Would only take a couple of minutes to do.
No rotoscoping necessary.

[Steve Crow]

I’ve done a quick test using the “Chroma Keyer” filter in the visual mode and I can see that it will work – however is there a way to limit the filter effect to just a portion of the frame, in other words to only key out a limited area of the white wall instead of the whole wall?

[Mark Suszko]

Yeah, you mask it as before.

If the bare wall the arm was moving across is blank white, you could try duplicating the track with the arm, stacking it with the fake art in between. Crop the art layer toshow just the inside of the frame. On the top duplicate layer, add another cropped mask that’s the same, go to modify>blend modes, and try “Screen” or “alpha matte” there. It will need level tweaking to work, certainly.

Another “poor man’s rotoscoping” tool is to export the clip from your timeline as an image sequence of targas or tiffs to a folder, open the folder in photoshop, and paint out around the subject with the erase tool and the magic wand. Re-save the stills right where they are, re-import them back to the timeline and they should be a perfect fit now, with alpha channel, as if they were green-screened. (Tip: put them in their own bin and make sure the duration for imported graphics is set at one frame). The quality of that roto is dependent on your tracing and photoshop skills somewhat, but it is cheap and easty to try, and may do the trick for the dozen or so frames the arm gets obscured.