Sky replacement question

T

Thilo-

New member
Fairly new to after effects.
I create a ramp gray mask to replace a washed out sky with a blue solid. It keys the sky fine, but there is part of a guy's shirt that is white which it won't differentiate as non-sky. How do I tell it to not key out that small area without going frame-by-frame and coloring the mask with black?
I'm sure there's many ways to do this, any suggestions are appreciated.
 
You can use the mask tool. Exactly how you'll use it depends on how you've set up your key, but you can basically duplicate your source layer, trace a shape around the shirt but not the sky with the mask, and move the mask around with keyframes if necessary. Put your sky layer on the bottom. If you have a semi-stationary well-isolated subject, it's a five-second fix.
 
Okay thanks. I did that tutorial and the sky correction works fine.
I've tried for hours and I can't seem to get the mask to keyframe.. I use the tracker but all it does is track the footage within the mask and not the mask data itself. Is there a secret to easily tracking a mask area?
 
You cant apply a track to a mask.
But you can apply the mask to a layer (duped footage or a solid) and then apply the track to that whole masked layer.
It's a work around. That way you only have to keyframe the mattes shape over time and let the track deal with its position.

AE handles masks as a series of points connected by splines. To AE a mask has no movement it only has point deformations, because it is a part of a layer and not an actual layer.
 
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