Nuke's merge node has 30 operations, and finding a Compositor who has utilized them all would be a difficult task. However, I want to shed some light on two merge operations that are incredibly useful, and don't get as much love as they should.
The most common operation, Over, is pretty self-explanatory: The image in the A pipe goes over the top of the B pipe. So how and why would this concept need to be expanded upon?
When working with CG renders that have baked-in holdouts, or if you're creating and precomping your own holdouts using Deeps, you might find that you get dark edges when merging everything back together. This is where disjoint-over can help! Let's take a look at a quick example to demonstrate:
