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Background Matting: The World is Your Green Screen

grail.cs.washington.edu

31–40 of 60 posts

Re: Background Matting: The World is Your Green Screen

#31
post #7

This is broadly called natural image matting if anyone is curious enough to look into the last 20 years of research.

Thank you!

(wouldn't it be nice if every time a research topic pops up here that there would be a small list of the essential keywords to look for more background information?)

Re: Background Matting: The World is Your Green Screen

#33
post #13

What's novel about this? If you have a background picture, you have all the info you need to identify your subject - just plain subtraction. I think this is what the Photo Booth app on my circa-2012 MacBook does, quite effectively.

Ex-VFX person here. Green screens are crap with hair, because its translucent the green/blue bleeds through which means that it has to be cleaned up by hand. Then there are the situations where there isn't a green screen. Again manual cleanup is required. Each frame needs to be cut out by hand. 24 times a second. The same with a difference matte. Cameras are noisy, so there is constant noise in the alpha channel. Thi…

Are there no tools that automate the cleanup of green-screen artifacts?

Re: Background Matting: The World is Your Green Screen

#34
post #28
post #21

Earlier quoted context omitted.

This new method works well for partially transparent regions (hair) and allows slightly larger background movement and color overlap between foreground and background.

I think they baited you with their "loook, movement" replacement videos. As far as I can tell, their inputs have a fixed background and are of constant exposure and camera position.

In the first example (the one with the girl), you can see that there are small camera movements. You can also see the effect this have when applying straightforward background subtraction in the second video.

Re: Background Matting: The World is Your Green Screen

#36
post #2

Is it fast enough to operate on a live video feed from, say, a webcam?

Yes. OBS offers it. Teams and Zoom have guesswork-based imitations.

OBS only offers a green screen plugin, and the teams/zoom versions are nowhere even close to this good.

Re: Background Matting: The World is Your Green Screen

#37
post #33

Earlier quoted context omitted.

Ex-VFX person here. Green screens are crap with hair, because its translucent the green/blue bleeds through which means that it has to be cleaned up by hand. Then there are the situations where there isn't a green screen. Again manual cleanup is required. Each frame needs to be cut out by hand. 24 times a second. The same with a difference matte. Cameras are noisy, so there is constant noise in the alpha channel. Thi…

Are there no tools that automate the cleanup of green-screen artifacts?

The green screen software itself is that tool. The parent is saying it has limitations
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