Understanding alpha channels


show more Understanding alpha channels provides you with in-depth training on Video. Taught by Chris Meyer and Trish Meyer as part of the After Effects Apprentice 02: Basic Animation show less
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Understanding alpha channels

Now if you remember, earlier in this lesson, when we imported our snowstorm title, After Effects asked us what type of alpha channel this layer had. At the time, we clicked on Guess, and After Effects correctly guessed that it was pre-multiplied with white. I thought it would be useful to explain, in a little more detail, the difference between straight and pre-multiplied. Now you will not see this dialog, unless the alpha channel is unlabeled. Unlabeled alpha channels may come from outside of the Creative Suite.

Photoshop, Illustrator, and After Effects always label their alpha channels, but if you don't ever see this dialog box, I do want to point out that there's a preference that someone may have set that will always get the dialog. Click OK and I'll show you Preferences > Import. The default is to always ask the user if After Effects comes across an unlabeled alpha. If someone had set this preference to Guess, After Effects will always guess, and sometimes it guesses in...

Understanding alpha channels
Video duration: 8m 34s 2h 19m Beginner Updated Nov 09, 2012

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Understanding alpha channels provides you with in-depth training on Video. Taught by Chris Meyer and Trish Meyer as part of the After Effects Apprentice 02: Basic Animation

Subject:
Video
Software:
After Effects
Authors:
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