If you spend a lot of time in Fusion, you may have noticed the “Pre-Divide/Post-Multiply” checkbox on many tools…
But what does it do?
Compositing is all a about math. Sometimes operations don’t get applied to just the part of the image you want.
You may apply a color corrector to a node that has transparency, but the effect ends up applying to multiple layers.
Pre-Divide/Post-Multiply is the solution!
In this video from VFX Study, you’ll learn about:
- 01:08 Color and Alpha Examples
- 04:50 Unpremultiplied Images and Manual Workflow
- 15:26 Numerical Example