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Difference Keyers

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Joe Busam
Difference Keyers
on Dec 30, 2009 at 3:48:02 pm

Hello peeps!

I'm neck deep in a motion control post project (a la Michel Gondry's Kylie Minogue music video) and was hoping to use AE's Difference keyer. However it doesn't seem to be very forgiving. Are there any 3rd party difference keyers out there that anyone could recommend? I'm looking to be delivered from rotoscope hell!


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Dave LaRonde
Re: Difference Keyers
on Dec 30, 2009 at 6:03:35 pm

Sorry, but your deliverance ain't comin' from Adobe... and frankly, I don't know if it's comin' from anybody else's difference keyer, either. Difference keying is a concept that looks good on paper, but stinks in practice.

AE's Difference Keyer is NOT bad at all, but like every difference keyer, it needs absolutely PERFECT footage in order to work properly. I'm talkin' 4-4-4 color-resolution, lossless footage... and almost nobody shoots that kind of stuff. Okay, George Lucas shoots it.

HDV is the absolute worst of the bunch, followed by DV, then there's everything else. Whaddya got?

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

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Steve Roberts
Re: Difference Keyers
on Dec 30, 2009 at 9:53:23 pm


The problem with diff keying (aside from noise) arises when FG and BG show areas of the same color ... which is usually around grays and browns.
Is there any way you can mess with levels & color correction on the footage to pull out any colors that might be similar between the two? (applying the same effect to the clip with talent and the clip without). Then you key, then use the keyed footage as an alpha matte.

It might work ...

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