I had this idea for an effect and I wanted to know if something like this has been done and if so how to do it:
I want a lighting effect for an action scene where I will have an area start lighting up, while I would like to simultaneously have another area start darkening in a similar manner, all in a (relatively) lit environment. I want an effect that looks basically in all ways like a light, but its something like a black-colored light that paints its surrounding black in a light-like way.
Basically I wanted to know if there is any way I can do some kind of post processing where I can use an LED as a green screen of sorts for the darkening effect. So wherever the LED is shining more or less maps to some kind of darkening effect/transformation.