How do I darken shadows from a shadow catcher in the compositor? I am working on a shot of a car sitting in a plane integrated into a video I shoot.
When I rendered the image sequence I separated the shadow from the car (when I was rendering the Car itself I disabled the Shadow catcher plane and vice versa) to give me more flexibility in compositing. Then I imported the shadow sequence and the car sequence in After effects.
When I am trying to darken the shadows more using curves the shadow is not affected with any change. I imported the sequence in blender compositor but the same thing happens.
Does anyone have an idea to solve this issue?
I would say, you should affect Alpha channel not the RGB values for correct result.

connect EXR alpha channel to RGB Curve node
to combine image and alpha channel back add Set Alpha node


RGB channels of Shadow Catcher probably does not contain any information at all.
Note: for images like PNG (without separate alpha channel listed) you can use Separate RGB node.