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Footage and alpha channels
If one has footage / clip that contains no alpha channel is there a way within AE to get one ? Now my current thinking is that it it’s not possible to get a really good alpha channel, at least one that could be used for masks or mattes. I’ve played around a little with some of the Alpha related effects but haven’t really dug in so I might be making a mistake but saying it’s not possible.
My other thought is to import video into Photoshop extended and then create the alpha from there but that is certainly labor intensive.
Anyone have any ideas ?
Thanks
Stuart -
4 Replies
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I’m no expert, but that’s what keying is all about, adding transparency to colors or luminosity:
Color Key
“Keylight” is very powerful and a separate instill of the disk I think.
Knoll Unmult (A FREEBIE):
https://www.redgiantsoftware.com/unmult.html
KNOLL UNMULT
Knoll UnMult is used to generate mattes for light effects or other bright elements generated on a black background. It is also the perfect solution to cleanly composite elements with pre-multiplied alpha channels.UnMult creates an alpha channel based on the maximum luminance of the RGB channels. It also makes the RGB channels “un-premultiplied”, giving you full access to the RGB values of an element without any alpha-based attenuation.
Aharon has some tuts on Alpha:
Understanding Straight vs. Premultiplied
https://library.creativecow.net/articles/rabinowitz_aharon/straight_vs_premult.phpHe uses Keylight, here;
Creating Super Tight Junk Mattes
https://library.creativecow.net/articles/rabinowitz_aharon/junk_mattes.php.
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Thanks Yikes, you gave me quite a bit to look into. I realized after I posted that AE creates an alpha channel regardless but it’s generally all white. So that was the differentiation as to what I’m looking for. Anyway I’ll pursue these links and tutorials.
Cheers
Stuart -
Calculations or Set Channel effects
Richard M. Harrington, PMP
Author: Photoshop for Video, Understanding Adobe Photoshop, and ATS:iWork
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Thank you Richard. Over the past few weeks I’m been brushing (no pun intended) on my masking skills in photoshop, so I now know that I can carry those over to AE.
However, in addition one tool that seems interesting is Matte Generator from Digital Film Tools. I haven’t seen anything around though that demonstrates the product except for a small photo on the DFT website. I kind of wonder why no one has a done a tutorial on it. And I’m not volunteering, at least not yet 🙂
Stuart
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