I am not sure if i explained it well in the subject title.. In my film, i have a painter who spreads black paint across a canvas. I want to change that black paint to black & white televisions snow (When the TV scrambles). Is there a way where i can just select a sample from somewhere and have it replace just that color? I am a novice to after effects. Any help would be greatly appreciated.
P.S I will post the piece of the video up if it will help.
You want the appearance of static painted on, right? (not black paint that becomes static).
You didn't specify whether the canvas fills the frame, so assuming it doesn't completely, I would duplicate the footage layer and mask off the canvas.
Add a levels effect and crush the blacks and pop the whites.
Add a full-frame layer of static - you can fake it with the Noise effect applied to a solid - to the comp, between the two footage layers.
Set the static layer's Track Matte to Luma Inverted.
I'm hoping this was shot locked-down - on a tripod. It's another can of worms if it wasn't.
If the painter's arm obscures the canvas at all, there may be shadow areas in the arm that won't get knocked out by the luma matte.
In that case you'll have to rotoscope the arm on the upper footage layer.