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choking a matte layer

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Elin grome
choking a matte layer
on Mar 18, 2010 at 5:59:47 pm

Hi guys,

I have a black and white layer which i am using as a luma matte...

the problem is that there's a bit of the background showing through so i would like to choke the matte a little bit; ie eat into the white area a little with 2-3 black pixels...

but because this is a luma matte the simple choke doesnt work - it only works on alpha areas...


can anyone help? :(


thanks in advance

Elin



It's all the those pesky details :p


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Samuel Hall
Re: choking a matte layer
on Mar 18, 2010 at 6:13:02 pm

I don't have AE in front of me right at this moment so forgive me if this doesn't work:

You could try pre-composing the layer and it's luma matte and apply a matte choke to the new pre-comped layer.

Samuel Hall
DP/Editor/VFX/Music
http://www.vimeo.com/samhall


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Dave LaRonde
Re: choking a matte layer
on Mar 18, 2010 at 6:13:40 pm

Turn it into an Alpha Matte, and use the matte choker! Done!

How do you turn it into an Alpha Matte? Use the Set Channels effect on your luma matte layer. You may have to precomp the layer to use AE's chokers, but that's no big deal....

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


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cowcowcowcowcow
Darby Edelen
Re: choking a matte layer
on Mar 19, 2010 at 8:33:49 am

You can apply a Channels > Set Matte effect to the black/white matte and set it to use it's own luminance as a matte, then apply the Matte > Simple Choker effect and use this layer as an alpha matte.

The alternative is using Channels > Minimax applied to the black/white matte set to a Minimum operation with a radius of 1 or 2. However, if there are subtle details in the black/white matte then this can end up chunkifying those.

These two different methods will have two different results, so try 'em both and see which works better.

Darby Edelen


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Elin grome
Re: choking a matte layer
on Mar 19, 2010 at 11:08:11 am

Darby - your first solution worked fine - but thanks guys, all interesting techniques...

Elin

It's all the those pesky details :p


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