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Fringing around white objects over greenscreen Primatte

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chris smith
Fringing around white objects over greenscreen Primatte
on May 13, 2010 at 2:22:23 pm

I'm using Primatte v4 on RED native (4K) footage. I've got people with white shirts in every shot, and I'm getting a dark fringe around wherever the white is composited over white. If I put it against a color, the fringing isn't noticeable. Can't use light wrap because they'll be walking in front of each other.

Matte choke, decrease opacity, fine tune seem to have no effect on this.

Thanks in advance for any help on this!





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Dave LaRonde
Re: Fringing around white objects over greenscreen Primatte
on May 13, 2010 at 3:11:27 pm

What happens if you turn the spill suppression off?

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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chris smith
Re: Fringing around white objects over greenscreen Primatte
on May 13, 2010 at 3:28:39 pm

Basically the same thing, only greener. This sample is without any of the correction applied as well.




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Dave LaRonde
Re: Fringing around white objects over greenscreen Primatte
on May 13, 2010 at 4:07:08 pm

I suppose it looks similar if you use Keylight to pull the key.
I further suppose that the footage is properly-lit for chroma key, and there's sufficient distance between the subject and the key background.

Is the footage in an 8-bit or 16-bit comp?



Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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chris smith
Re: Fringing around white objects over greenscreen Primatte
on May 13, 2010 at 4:23:30 pm

It was pretty well lit, yes. The footage is in a 16bit comp. I also tried 32 bit float.

And thanks so much for your response to this!





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Dave LaRonde
Re: Fringing around white objects over greenscreen Primatte
on May 13, 2010 at 4:54:54 pm

Well, that's frustrating.

If you can't delve into the more arcane controls of the keyer to make the key look better, how about adding one of AE's chokers after the key? Unless you're trying to key wispy blonde hair at the same time, it ought to work, albeit admittedly crude.

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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chris smith
Re: Fringing around white objects over greenscreen Primatte
on May 13, 2010 at 5:08:03 pm

Right, which is what I've been attempting for the last few hours.

But it's strange that I would have to fight the keyer like that. It's almost as if it is adding pixels from the matte to the fringe area. So it's only visible when compositing white foreground and white background.

Thanks for your help. Maybe someone at Red Giant will have an idea or two as well.



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Dave LaRonde
Re: Fringing around white objects over greenscreen Primatte
on May 13, 2010 at 11:26:47 pm

[chris smith] "Maybe someone at Red Giant will have an idea or two as well. "

I certainly hope so. Call it coincidence, but just yesterday another person had troubles with Primatte and good chroma key footage:

http://forums.creativecow.net/thread/2/978728

It makes you wonder.

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Todd Kopriva
Re: Fringing around white objects over greenscreen Primatte
on May 16, 2010 at 1:49:37 am

BTW, the Refine Matte effect in After Effects CS5 has some options for decontaminating edge colors---removing background colors from foreground objects at matte boundaries.

This effect was created to help with Roto Brush, but we also split it out separately specifically to help with mattes like yours that are created through other means.

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