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fxgogo
05-20-2005, 06:05 PM
I have two layers, one with a rgb image, the other with a animated alpha layer.

I want to combine the two and retain rgb information when rendering out the final sequence.

I tried the 'shift channels' effect and renderering 'straight alpha', but AE still cuts all the RGB away in the render.

I am feeling really stupid here. It is such a simple thing to do, and a PS action woulddo the trick but I want the final output to come from AE.

Any ideas?
AAAron
05-20-2005, 06:30 PM
effects-> channel -> set matte

or place the alpha layer over the image layer, select the image layer and choose

layer -> track matte
fxgogo
05-20-2005, 09:08 PM
That gives me the same effect, in that it cuts the RGB info away. The effect I am wanting would be achieved in PS by copying the alpha channel from one image and pasting it into the alpha of the RGB image.
AAAron
05-21-2005, 12:03 AM
Not sure I understand what you mean? The above, should not make the image grayscale. Is the alpha layer a "empty image with an alpha" or an alpha in it self (a gray scale image)?

To use the trackmatte you need to hide the layer used as alpha otherwhise it hides the image thatīs takes use of the alpha. Same goes for the "set matte" effect.
Voitek
05-21-2005, 09:14 AM
Aaaron is right. Set matte and track matte is the solution. You can also use channel combiner, but you really don't need nothing more complicated than track matte. Their effect depends on the footage though.
Put the alpha layer over the rgb layer and check every option from TrkMat column (alpha/inv alpha/luma/inv luma).
If it doesn't work, you don't have any transparency in your footage OR you don't interpret it correctly. Select the file in the project window, choose the interpret footage and select the right option.

cheers
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05-21-2005, 09:15 AM
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