Adding Alpha Channels

[Tim Kurkoski]

Alpha is kind of automatic in AE. There are many different ways of making parts of your layer transparent, so it really depends on what you want to do with the layer. You can:

* Draw a mask
* Use a blending mode
* Use a track matte
* Use a keying effect

You can look up any of those in the help files. But if you want to be more specific as to what you want to do with your layer, I’m sure we can give you a more specific answer.

[Michael Duff]

test your alpha by clicking on the little white square at the bottom of your comp window (next to the red/green/blue little squares). Or set your background colour to something like hotpink so you can see what will be transparent.

Make sure when you render that you set your export settings to include an alpha channel, or RGB+A, or 32bit. Rendering as a TGA sequence is a pretty safe format that most NLE’s will be able to read the alpha. Otherwise quicktime animation codec or AVI uncompressed are good too.

Cheers

Michael Duff –
Southern Cross Ten, Australia