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Photoshop Alpha Channel in After Effects not working

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Zack MulvaneyPhotoshop Alpha Channel in After Effects not working
by on Sep 5, 2011 at 8:12:55 pm

I created this basic PSD file:



And then created the following alpha channel for it with the goal of bringing the file into after effects and (1) animating the blue circle and (2) dropping a .MOV file into the comp that will only play on the alpha channel. But when I open the PSD file in AE and put the .MOV file as the bottom layer in the comp, I can't see the .MOV video -- rather, I just see the black shape. Could someone please advise me as to what I'm doing wrong?



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Kevin CampRe: Photoshop Alpha Channel in After Effects not working
by on Sep 5, 2011 at 11:03:39 pm

i think your alpha is inverted... white is opaque and black is transparent, so anything you want to see should be white in the alpha and anything that you want to be transparent should be black.

also, if you use psd files in ae, you don't need an alpha channel. transparency in a layered psd file (the areas where you see the checkerboard) will be transparent in ae when you import it, without needing to create an alpha.

Kevin Camp
Senior Designer
KCPQ, KMYQ & KRCW


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Kevin CampRe: Photoshop Alpha Channel in After Effects not working
by on Sep 8, 2011 at 2:58:06 pm

i really must apologize for that major brain fart... your alpha was correct. you should have seen the black shape get knocked out from the rgb channels.

as for why the alpha didn't show up in the file. it may be that the alpha wasn't named 'alpha' or 'alpha 1' in the channels panel in photoshop, or maybe the when the psd was saved, the alpha check box wasn't checked, or if you created a targa (or similar), checked the alpha box, but then saved as 24-bit rather than 32-bit, then it would have lost the alpha.

as for the transparency i was talking about. it looks like you have 3 layers (green background, black square, blue oval). you really don't need the black square, you just need a hole that shape in the green layer.

there are a variety of ways to do that, an easy way is to select the green layer (needs to be a layer, not a background), then drag the black layer to the layer mask icon on the layers palette. this should add a layer mask to the green layer in the shape of the black square, but it is the reverse of what you want.

then simply invert the layer mask (select layer mask and choose layer>invert). hide the black square layer and you should see the transparency that you need. delete your alpha channel (not the layer mask), save and import into ae and you should see the same transparency.

Kevin Camp
Senior Designer
KCPQ, KMYQ & KRCW


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Zack MulvaneyRe: Photoshop Alpha Channel in After Effects not working
by on Sep 5, 2011 at 11:10:24 pm

No, my alpha is as intended. Everything in the black area I want to be transparent b/c I want to have video showing through that black area (think of it as a picture frame for my video).

Maybe I'm not understanding transparency correctly, but I can't simply make that shape transparent b/c I have that green layer behind it. So, If I drop my .MOV file just beneath the transparent layer in AE, you won't be able to see the green layer. And If I drop my .MOV file beneath all the layers PSD layers in AE, the .MOV file will be covered up by the green layer. Am I missing something...?

Thanks for the quick reply, btw.


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Michael SzalapskiRe: Photoshop Alpha Channel in After Effects not working
by on Sep 6, 2011 at 5:28:47 pm

I don't understand why you need to be creating an alpha channel in Photoshop anyway. PS files come into AE with all the transparency intact.
You can then duplicate layers as needed in After Effects and use them as track mattes.

- The Great Szalam
(The 'Great' stands for 'Not So Great, in fact, Extremely Humble')

No trees were harmed in the creation of this message, but several thousand electrons were mildly inconvenienced.


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Darby EdelenRe: Photoshop Alpha Channel in After Effects not working
by on Sep 7, 2011 at 12:45:30 am

You can copy the vector mask from your black shape, paste it on your green layer, set it to the 'subtract' mode (accessible when using one of the selection tools 'v' or 'a' and with the mask selected). Then you can delete your black shape layer.

Alternatively you could import the psd as a composition and work with the individual layers that way (use the black shape as an alpha inverted track matte). Or you could make your solids in AE to begin with.

Darby Edelen


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Zack MulvaneyRe: Photoshop Alpha Channel in After Effects not working
by on Sep 8, 2011 at 5:06:18 pm

Thanks for all the feedback, everyone. I think the best solution is to just cut out that shape rather than messing around with alpha, as some of you have suggested. Thanks again!


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