Join Mark Christiansen for an in-depth discussion in this video Prevent alpha channel fringing, part of After Effects Compositing: 1 Intro to VFX.
- So as I said, if your selections are generated…by the computer, there's one thing that can come up,…which has to do with alpha channel premultiplication.…Now, that's a very complicated way of saying fringing.…And so if you ever see a foreground come in…with black fringes around the edges,…you know that you have a premultiplication problem.…This text was created in Photoshop…and here you can see a transparency layer.…So with a transparency layer,…there's not going to be any background…mixed into the foreground.…
It's often the case, however,…that you don't work with transparency data,…but instead with an alpha channel.…Now, if I go into Interpret Footage, Main,…I can ignore the alpha channel that's in this TIFF image.…And now you can see that everything looks just fine.…There's nice feathering of the edges against the background,…but of course we don't have a selection anymore.…If I go to the alpha channel,…you can see it's just turned off.…So, instead what we want to do…is go into the same Interpret Footage settings…
Skill Level Intermediate
Q: This course was updated on 06/22/2017. What changed?
A: The following topics were updated: an overview of moving selections; an overview of the camera for compositing; and an overview of what makes an image cinematic.