AlphaBender

Change log

v1.1

• Fixed a bug that caused the alpha to change wrongly when weight < 0 even if hardness = 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