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Keylight "Intermediate Result" applies Alpha Channel to RGB Channels - no multi pass keying possible

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Christian Haker
Keylight "Intermediate Result" applies Alpha Channel to RGB Channels - no multi pass keying possible
on Jun 24, 2010 at 3:08:02 pm

Hello,
I'm trying to do some multipass keying on a green screen material with the keylight plugin Version 1.2v10. The Keylight manuel says " Intermediate Result - is used for multipass keying. The alpha is set as per normal, but the RGB values are not modified from the original source image." When I use "Intermediate Result"; I get the source image with the alpha channel applied to it. Which means that there ist no green screen left for the second keying path. What did I do wrong. Do I have to tell after Effect not to apply the alpha channel? If so, how would I do it?

I'd be very gratefull for any help.
Christian.


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Kevin Camp
Re: Keylight "Intermediate Result" applies Alpha Channel to RGB Channels - no multi pass keying possible
on Jun 24, 2010 at 3:51:54 pm

i believe there is a tip in the manual that uses two instances of keylight (this may be what you are working with)...

the trick here is that, by default, keylight ignores the alpha of a layer it is applied to, unless you tell it how to use it.

so (by the tip in the manual) the first instance creates a very tight matte to be used as an inside mask (like a core matte) for the second instance. so you need to define the inside mask settings to add the source alpha to the inside mask (rather than ignore).

Kevin Camp
Senior Designer
KCPQ, KMYQ & KRCW


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Christian Haker
Re: Keylight "Intermediate Result" applies Alpha Channel to RGB Channels - no multi pass keying possible
on Jun 25, 2010 at 9:53:30 am

kevin, thanks for your answer.
Thats exactly what i want to do. I want to use two or even three instances of keylight. The first instance creates a tight matte, which is used by the second instance. the second instances uses the alpha channel of the first instance and adds it to its inside maks. correct.

BUT my problem is, that the first keylight instance doesnt pass the original RGB values of the original footage to the second instance, ALTHOUGH I set the view of the first keylight instance to "intermediate result". Instead of leaving the original RGB values unmodified and just adding the matte in the alpha channel, it applies the alpha values to the RGB values. So the image has no green screen when it enteres the second keylight pass.



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Kevin Camp
Re: Keylight "Intermediate Result" applies Alpha Channel to RGB Channels - no multi pass keying possible
on Jun 25, 2010 at 1:40:44 pm

sorry, i was mistaken about how keylight handles an alpha by default (or they changed it since i used this method)...

in the inside mask properties, the default for source alpha is set to 'normal', change that setting to 'add to inside mask' and you should then be able to 'see the green' to set up the keying settings for the second keylight effect.

Kevin Camp
Senior Designer
KCPQ, KMYQ & KRCW


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