It is my understanding that you use the Compositor for post-production, after rendering the scene. Now I would like to build several "scenarios" for post-production. For instance a node tree that does some color corrections and a node tree that does all kind of fancy stuff with the rendered image. And I want to chose which "scenario" I apply. Is this possible in Blender ? I had the idea to do that with render layers but that does not seem to work. Currently I can only think of building several blend files but that has clearly some disadvantages. How to build different post-production scenarios in Blender ?
I see a couple of options:
1 Using a new scene.
Without having to create new files you can use a new scene with linked objects. Changes in the compositor for one scene will not affect the compositor options for other scenes:
2. Using a a Switch and/or Split viewer node
The switch node allows you to re-route the node flow, so you can compare different inputs:
A split viewer node creates a viewer that allows you to compare both inputs simultaneously, by splitting the window horizontally or vertically.