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Matte Choker on Precomp

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Dale PaquetteMatte Choker on Precomp
by on Oct 15, 2010 at 10:55:51 am

I'm following up on a 2008 thread answered by Kevin Camp (that I can't find a second time). I created a simple inverted luma track matte and then precomposed. I want to choke the matte a little but when looking at the channels, there is no alpha channel. The best I can achieve so far is to pre-render. Is there a better way? Thanks, Dale


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Walter SoykaRe: Matte Choker on Precomp
by on Oct 15, 2010 at 12:31:46 pm

[Dale Paquette] ". I created a simple inverted luma track matte and then precomposed. I want to choke the matte a little but when looking at the channels, there is no alpha channel."

What did you precompose? If you precompose both the track matte layer and the fill layer in the same precomp, you'll be able to use the Matte Choker on the precomp.

If you only precomposed the track matte layer, you'll have to either include both track and fill in the precomp, or apply Matte Choker to the matte layer.

Walter Soyka
Principal & Designer at Keen Live
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
RenderBreak Blog - What I'm thinking when my workstation's thinking
Creative Cow Forum Host: Live & Stage Events


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Dale PaquetteRe: Matte Choker on Precomp
by on Oct 15, 2010 at 12:45:31 pm

Thanks for getting back to me. I duplicated the foreground subject layer and converted the new (top) layer to B&W. I then set the the original (bottom) layer to inverted luma matte. These were then laid over a BG layer and it worked exactly as it should except that there was a "fringe" around the FG subject. I then tried to use the simple matte choker and quickly realized that it's the two layers together that have transparency. So, I selected those two layers and pre-composed. When I looked at the channels of the pre-comp, there was no alpha channel - rather the pre-comp seemed to be just transparent in places (where it should be). If I tried to add the matte choker, AE (CS5) would not allow it. So, I then pre-rendered the pre-comp and it worked fine when I substituted it for the pre-comp. Hope my explanation is clear! Dale


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Walter SoykaRe: Matte Choker on Precomp
by on Oct 15, 2010 at 12:55:38 pm

[Dale Paquette] "When I looked at the channels of the pre-comp, there was no alpha channel - rather the pre-comp seemed to be just transparent in places (where it should be). If I tried to add the matte choker, AE (CS5) would not allow it."

Your process should work as described, so there's something else going on here.

With a background visible, you won't see any alpha if you're in the comp viewer. If you solo your precomp, you should be able to see its alpha in the comp viewer.

As for AE not allowing you to apply the matte choker, are you sure you haven't locked the precomp layer?

Walter Soyka
Principal & Designer at Keen Live
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
RenderBreak Blog - What I'm thinking when my workstation's thinking
Creative Cow Forum Host: Live & Stage Events


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Dale PaquetteRe: Matte Choker on Precomp
by on Oct 16, 2010 at 10:26:43 am

Walter, guess I should be in AE basic. To close this out, a new day, a new result. Yesterday, I could not make it work, today it does. Thanks for you support. Dale


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