Undo a merge "over" operation using your merged layers and the A input.
Unmerge
First submitted: 20 September 2025
Updated: 24 September 2025
Author: Kesher
Compatible Nuke versions: 13.0 or later
Compatibility: All, Source
Unmerge uses a reverse-engineered "over" expression to output the original B layer of a merge "over" operation. Plug your original A layer (your top layer) into the A input, and your merged layers into the B input. Areas where your A layer has an alpha of 1 will be black, since the A layer has fully occluded the B layer.