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applying effect to layer based on its alpha channel
Hello,
I’m diving into the world of alpha channels and after effects for some cool special effects. I have a 3 second shot of a red car driving down the street, and I’d like to treat the footage so that the car retains its color while everything else is black and white (think ‘pleasantville’).
The way I’ve decided to do this was to:
1. Export the footage as a targa sequence.
2. Bring the targa files into Photoshop, create alpha channels where the white pixels represent the red car and the black pixels represent everything else.
3. Bring the sequence back into AE, drop it into a comp as a layer.
4. Apply an effect on the sequence layer which looks at the black part of the alpha channel, makes that part of the sequence black/white, and leaves the rest alone.However, I’ve discovered that when you bring the sequence into ae, the interpretation remains fixed to the file, and when I drop it into a comp, the background disappears. I have to then bring in a second instance of the sequence, tell it ‘no alpha’, then drop it right below the interpreted layer before adding the saturate/hue effect, giving the impression that the car is red and the rest is black/white.
Mind you, this does work the way I want it to, but I was wondering none the less if there was a way to do it with only one layer.
Take care,
Nick
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3 Replies
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yes. the filter’s name is “leave color”. it’s under stylize.
p
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Take a look at this tutorial of mine to get more ideas 2 or 3 color effect
Cheers
Roland KahlenbergbroadcastGEMs.com – the leader in customizable royalty-free animated backdrops
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leave color and rotoscope out sections of the color that are close to the one you select
Tom Small
2nd year Film/Video editing major, SVA NYC
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