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Batch converting an alpha channel to white?
I have a project where I need to convert thousands of greenscreen converted talking head videos from a regular alpha background (pre-multiplied to black) to a white background.
So basically from this:
https://www.emoclients.com/temp/BlackBgrndWithAlpha.mov
(the black is the alpha channel after removing the greenscreen)To this:
https://www.emoclients.com/temp/ExampleWhite.movI found I could script this using Photoshop CS4 Extended, but it strips off the audio.
If anyone knows an FCP plugin to do this, I can batch it out of FCP.I’d be very appreciative of any of your ideas!
Thanks!
Paul Lundahl
Creative Director / Partner
eMotion studioshttps://www.emotionstudios.com
____________________________________________________________________US:
85 Liberty Ship Way, Suite 110 Sausalito, CA 94965
p: 415-331-6975 f: 415-331-6124
Japan:
101 Akasaka TM flat, 7-6-16 Akasaka 7chome, Minato-ku Tokyo, Japan #107-0062
p: 81-3-5562-5300 -
2 Replies
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Hi Paul,
FC can only export Strait Alpha channels.
No premultiplied in Black neither n White.
You need to do that with FC, Combustion.
Motion can export with Premultiply Alpha but no choice of Black/White, so I guess is always in Black.
Cheers,
rafael -
[Paul Lundahl] “I have a project where I need to convert thousands of greenscreen converted talking head videos from a regular alpha background (pre-multiplied to black) to a white background. “
But we’d have to ask, “Why? What software are you moving these clips into that requires white premultiplied alphas?”
Running a script in After Effects probably would not be very difficult.
https://help.adobe.com/en_US/AfterEffects/9.0/WS3878526689cb91655866c1103906c6dea-7f7ea.html
https://kb2.adobe.com/cps/143/tn_14326.htmlYou may already know this stuff but future seekers may wish to understand the differences:
https://www.digitalartform.com/alphaChannel.htm
https://www.ypoart.com/tutorials/alpha/fundamentals.php
https://www.icongalore.com/xp-icon-articles/alpha-channel-explained.htm
https://en.wikipedia.org/wiki/Alpha_compositing
https://en.wikipedia.org/wiki/User:Lkesteloot/premultiplied_alpha
https://toolfarm.com/tutorials/alpha.html
https://www.teamten.com/lawrence/graphics/premultiplication/bogiesan
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