There haven’t been that many (B&W) negative workflows here.
These two threads might be of interest:
These are negadoctor related though. This module is not yet a part of the latest stable (3.0.2), but this module is available in development and will be part of the August 10 stable 3.2.0 release.
I do mention this, even though it might not help you right now, to make sure that you do not start building a workflow around the (in my opinion flawed) invert module. It is definitely worth waiting 'till August for this new module. It is rather nice!