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Premultiply – matted with color
I have a layer with transparency which needs premultiplying with black but I would rather not render it out in order to apply the standard interpret footage method as it will create a massive intermediate render.
Is there a way to achieve this same premultiplying effect on a single layer (using AE CS5)?Many thanks
GrahamGraham Macfarlane
3D animator and VFX specialist
London UK -
7 Replies
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This tutorial may give you the answer you are looking for:
https://library.creativecow.net/rollason_ben/lens-flare/1Tudor “Ted” Jelescu
Senior VFX Artist -
Could you explain a little more about what it is you have and what you’re doing with it? I’m having a hard time figuring out why you’d need to premultiply footage for a workflow within AE.
Are we talking about removing premultiplication?
Darby Edelen
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Channel Combiner has a straight-to-premultiplied option.
Solid Composite will let you stick a black matte behind your transparent layer.
But, like Darby, I’m curious as to why you want pre-multiplication in AE.
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 -
Tudor, thanks for the link. Very useful info there!
Darby and Walter,
I have an asset containing coloured blurry graphics against black (no alpha channel) which I wanted to be against white. When Track Matting the asset in AE to make an alpha and using this over a white background one sees dark fringing in the blurry edges of the graphics.I could have rendered out the asset with this alpha and then loaded it back in and interpreted the footage using, Premultiplied – Matted with colour (black) but I wanted to avoid the extra file space usage of an intermediate asset.
The Channel combiner effect does exactly what I need!
Many thanks for your help guys!Graham Macfarlane
3D animator and VFX specialist
London UK -
You can also use Red Giant Software’s free UnMult [link] next time you need to remove a black background from a semitransparent object.
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 -
Downloading now!!!
Cheers!Graham Macfarlane
3D animator and VFX specialist
London UK -
Happy to help!
I was a little thrown by your original question, because AE doesn’t really expose premultiplication to the user like many other compositors do, but it all makes sense now.
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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