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Selecting people only from a video clip by their motion?
I want to use a graphical background layer and place some video of some people in the foreground. The problem is the video was shot outside, with varying colors in the background so Chromakey won’t work.
Is there a way in Final Cut to select a person or people, by their motion compared to the background, and fade the back ground to transparent?
Thanks,
Brian
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4 Replies
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That would be sweet indeed, but I don’t think you are going to find anything like. Sorry.
Best,
Eli -
Nope…this will fall under the catagory of ROTOSCOPING, and is best done…slowly and painstakenly I might add…with After Effects or Shake.
Next time, plan for this and shoot in front of a Green screen. Or go re-shoot it now.
Visual effects have to be carefully planned ahead of time…even something this simple.
Shane
Littlefrog Post
http://www.lfhd.net -
Yes. Sort of. Maybe. And sometimes Not.
The Difference Key is the filter you would have to use here. This filter allows you to mask out any pixels in a frame that are the same as in a reference image (your “Clean Plate”). You find frame that has none of the moving people in it, save it as a still picture, re-import it as your clean plate. You add the Difference Key to your video, open the filters tab and drop your clean plate into the image well. Adjust the threshold and tolerance and it all works, except….
Where it doesn’t work:
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Yes, you have in FC the “Difference Matte” that should extract the differnece in between two pictures, so if you put a background and the same background with people, shoukd key that people. I tried tat long ago with DV footage and the results are very poor. i guess if you work with better quality pictures you could get something OK. The same filter exist in Combustion and in AE (Keying>Difference).
Rafael
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