Fast & precise eroding of alpha channel
AlphaBender
First submitted: 12 September 2021
Author: Fynn Laue
Website: https://fynnlaue.com
Compatible Nuke versions: 10.0 or later
Compatibility: Linux, Mac, Windows
Change log
v1.1
- Fixed a bug that caused the alpha to change wrongly when
weight < 0even ifhardness = 0 - Improved accuracy especially when dealing with large, blurry areas
Modifying alpha channels is probably one of the things I do most when compositing. I've found Nuke's Erode and Dialate nodes to be a bit too limiting and slow for many of these operations. So I made this lightweight tool for growing and shrinking the alpha channel. It works well for both small adjustments, like 'leaning' the center of a gradient slightly towards one side, and big modifications.
Also useful for things such as:
- Despotting a key
- Smoothing out jagged edges
- Making big mask expansions/contractions
How to use
First you 'prep' the alpha channel to only show what you want to use as a base:
Then you 'bend' the result of prep to grow or shrink and add some blur if needed:
Modifying a simple linear ramp illustrates how the hardness and weight knobs affect gradients:
Inner workings
Runs on Blur and Grade nodes so it's simple and fast
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