After Effects - Output Alpha still renders background colour

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hasher22
Met Resolume in a bar the other day
Posts: 4
Joined: Thu Apr 25, 2019 13:45

After Effects - Output Alpha still renders background colour

Post by hasher22 » Sun May 05, 2019 02:43

Hey guys,

I have AE v16.1.1 (build 4) and the DXV 3 output installed.

Every time I render out a composition on settings:
- DXV 3
Video Output
- Normal Quality, With Alpha
Channels: RGB +Alpha
Depth:: Millions of Colors+
Color: Premultiplied (matted)

The background colour renders with it. I had my background colour to a lime green colour. I have toggled the transparency grid in AE and yes the checkered pattern shows and the lime green colour disappears. I know the background should not be rendered with the setting alpha. I have no solids either in my comp.

Hmmmm?>

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francoe
Is seriously in love with Resolume. Met the parents and everything
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Joined: Thu Nov 27, 2008 23:30

Re: After Effects - Output Alpha still renders background colour

Post by francoe » Tue May 07, 2019 02:15

I think DXV has no chance to screw up things on that side, is just AE.
Check if you're rendering with Premultiplied (matted) instead of straight alpha.
I bet you're premultiplying by lime, tasty but wrong for alpha creation. :mrgreen:

Joris
Doesn't Know Jack about VJ'ing or Software Development and Mostly Just Gets Coffee for Everyone
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Joined: Fri May 22, 2009 11:38

Re: After Effects - Output Alpha still renders background colour

Post by Joris » Tue May 07, 2019 08:41

How does the background color factor into premultiplication when alpha is zero? Zero times lime is still zero.

If you're seeing lime where there shouldn't be lime, my guess is you are rendering straight and interpreting premultiplied.

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