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Any ideas on keying very grainy footage?

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Marcin Staszewski
Any ideas on keying very grainy footage?
on Mar 5, 2014 at 11:01:01 pm

Hello guys,

I received some clips shot on some older sony film camera. The shots were scanned to ProRes 422 and delivered to me.
It's a simple scene, just dolly closing in on a standing woman with small green screen behind her.
One problem may be the light, which is set to around 2800K to imitate HPS street lamps (basically everything is yellow-orange-ish).
When I'm pulling the key edges become sharp and change drastically every frame no matter the setting I use in keylight.
The effect looks terrible and there is no way to reshoot...

Any ideas what to do in such cases?
I can add that the clip is pretty long (around 4 minutes) so any degraing would probably take ages.

One clever idea I found on the web somewhere was to average the matte over a few frames - this is very helpful especially that the woman isn't moving a lot, the result is still below average...


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Joseph W. Bourke
Re: Any ideas on keying very grainy footage?
on Mar 6, 2014 at 12:20:10 am

You don't say what version of AE you're trying to do this with. I'll assume at least CS6. I think you're better off trying to use the Roto Brush to do this than to try to pull an improperly lit key.

That said, you could try color correcting the shot by duplicating the layer, doing your color correction, then using the alpha you get there on the original footage. There's no substitution for lighting a key properly (separate lighting setup for the green screen), so there may be no alternative but to use the Roto Brush. If you're not familiar with it, don't just start poking around - learn it from the Adobe tutorials:

http://blogs.adobe.com/aftereffects/2010/04/roto-brush-in-after-effects-cs....

Joe Bourke
Owner/Creative Director
Bourke Media
http://www.bourkemedia.com


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Marcin Staszewski
Re: Any ideas on keying very grainy footage?
on Mar 6, 2014 at 12:48:11 am

Yes, I'm using CS6.
Oh well, I guess you're probably right... but wouldn't roto brush ignore the little details like hair and stuff?
I'm going to give it a try anyway (thanks for the idea!), but if any of you guys comes up with another idea please share it with me :)


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Joseph W. Bourke
Re: Any ideas on keying very grainy footage?
on Mar 6, 2014 at 3:18:16 am

There are guys here much better versed in keying than I am. You may get some alternatives. You may be able to feather the mask a bit after you Roto Brush (with some of the new mask tools), but it won't give you the fine hair key you're looking for. But, that said, to get a fine hair key, it has to be lit correctly, which doesn't sound like what you've got.

Variable width mask feathering might help out:

https://www.video2brain.com/en/lessons/variable-width-mask-feathering

Joe Bourke
Owner/Creative Director
Bourke Media
http://www.bourkemedia.com


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Dave LaRonde
Re: Any ideas on keying very grainy footage?
on Mar 10, 2014 at 11:06:22 pm

If the shot's as bad as you say it is, you'd lose edge details ANYWAYS in all the noise. Rotobrush at least gives you a fighting chance to salvage it.

Dave LaRonde
Promotion Producer
KGAN (CBS) & KFXA (Fox) Cedar Rapids, IA


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Marcin Staszewski
Re: Any ideas on keying very grainy footage?
on Mar 11, 2014 at 8:32:56 am

I got best results by mixing some techniques.
I averaged the matte, and in some parts where it still looked horrible I rotoscoped it manually by tracking the person's belt and assigning the data to a solid. Then I only needed to adjust the mask with few keyframes.
I tried roto brush but the clip is too long and I couldn't force it to calculate a specific area over the entire clip... after 20 seconds it started to lose the data in the beginning of the shot.


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