Change log
v1.1
- Fixed a bug that caused the alpha to change wrongly when
weight < 0
even ifhardness = 0
- Improved accuracy especially when dealing with large, blurry areas
About
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.
Available on Nukepedia here
Also useful for things such as:
- Despotting a key
- Smoothing out jagged edges
- Making big mask expansions/contractions
- Pre-processing alpha for edge extension
How to use
![First you "prep" the alpha channel to only show what you want to use as a base](https://www.notion.so/image/https%3A%2F%2Ffile.notion.so%2Ff%2Ff%2F9fcd4f23-a447-431a-87ca-4fd9a25617e9%2Ff3b0b1ce-f59e-49fe-bb50-0f9caac98dc2%2FalphaBender_demo02_v002.gif%3Fid%3D093b82a9-bc71-41a6-8e6e-827e243adbc3%26table%3Dblock%26spaceId%3D9fcd4f23-a447-431a-87ca-4fd9a25617e9%26expirationTimestamp%3D1722110400000%26signature%3D700sdnurDbQjzRTaMKEtHqEH0zNQ1zFKmfquhm3yJwA?table=block&id=093b82a9-bc71-41a6-8e6e-827e243adbc3&cache=v2)
![Then you "bend" the result of prep to grow or shrink and add some blur if needed](https://www.notion.so/image/https%3A%2F%2Ffile.notion.so%2Ff%2Ff%2F9fcd4f23-a447-431a-87ca-4fd9a25617e9%2Ffcc85484-6707-4539-ab0d-5029e3b1bb11%2FalphaBender_demo02.gif%3Fid%3D54e6eb70-62a7-4c1f-b98d-872ae46e6bf5%26table%3Dblock%26spaceId%3D9fcd4f23-a447-431a-87ca-4fd9a25617e9%26expirationTimestamp%3D1722110400000%26signature%3Dqgr7QL7svaDtkbzOrQPP2cbX99cUakvEryKxhnUPXTU?table=block&id=54e6eb70-62a7-4c1f-b98d-872ae46e6bf5&cache=v2)
![Modifying a simple linear ramp illustrates how the hardness and weight knobs affect gradients](https://www.notion.so/image/https%3A%2F%2Ffile.notion.so%2Ff%2Ff%2F9fcd4f23-a447-431a-87ca-4fd9a25617e9%2Fab8053c9-8b4d-46d5-b025-327ae8948af4%2FalphaBender_demo03_v003.gif%3Fid%3D94482116-37ff-4e12-ab2c-9430b481382a%26table%3Dblock%26spaceId%3D9fcd4f23-a447-431a-87ca-4fd9a25617e9%26expirationTimestamp%3D1722110400000%26signature%3D96qJgYIEvSqucsKI7_iX4sMR6gF3Pq771bB_M87ZWwA?table=block&id=94482116-37ff-4e12-ab2c-9430b481382a&cache=v2)
Inner workings
![Runs on Blur and Grade nodes so it's simple and fast](https://www.notion.so/image/https%3A%2F%2Ffile.notion.so%2Ff%2Ff%2F9fcd4f23-a447-431a-87ca-4fd9a25617e9%2F743ce8e4-07e3-4587-8649-394f335adef1%2FalphaBender_v1.0_nodegraph.png%3Fid%3De118a708-46a1-4a4f-90b7-a5a60ebc9d5b%26table%3Dblock%26spaceId%3D9fcd4f23-a447-431a-87ca-4fd9a25617e9%26expirationTimestamp%3D1722110400000%26signature%3DtOisAt2p4St2cgBqmiPWm_ZNX385Gsx2dCUfr30HcFU?table=block&id=e118a708-46a1-4a4f-90b7-a5a60ebc9d5b&cache=v2)