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Adobe After Effects Tutorial : Difference Matte
Hey, I recently found out a great way to Key a footage, without a green screen, and it takes only a few seconds !
But it requires a steady footage to work, I do not know if this has been posted already but, I just love this “discovery” of mine, and I hope it will help, at least 1 person hehe 🙂
What we will basically 2, is isolate a footage, the theory, is filming a X footage, or even taking a picture of this X footage, and then, filming the exact same X footage, but with your “actor” or anything you want to key, then adding the difference matte, and basically, Isolate the object.
For this tutorial, I used 2 simple images, available here
admire my artist work on paint :Background 1
Background With Blue
First Off, import the BG.bmp in Adobe after effects :
Then, under it, import the BGWithBlue.bmp
Then, selecting the BG.bmp, go in Effects->Keying->Difference Matte
Then, in the Difference Layer, select the BgWithBlue
And, in the view select the Matte Only
Then, in the BgWithBlue TrackMatte, select the Luma Matte Bg
And here is the result, your Isolated object :
This can be really usefull, if you can’t afford a Tripod, it’s really easy to make and use.
Hope it helps
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1 Reply
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Nifty!
I believe this is known as “fixed plate” or “clean plate” matte extraction. Something like that. With video footage (and a locked-down camera) it’s a little trickier, because the pixels aren’t *exactly* the same on every frame. Differences can be reduced by disabling the camera’s autofocus & autobrightness. And then in AE futz with blur and threshold and garbage mattes and the like and you can eventually pull the moving object from the background.
(And a fun thing to do is “unlock” the camera with panning &c after the fact; I did an experiment with that; youtube here.)
Also! This feature is built into Apple’s iChat video-chat software, they call it “Backdrops”. Doesn’t look *great* but it’s amusing.
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dvb == recreational pixel abuse // motion, graphics, & scripting
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