Blue alpha edges

[Simon Ubsdell]

You can simply use the Channel Blur effect and operate on the Alpha Blurriness only.

Simon Ubsdell
tokyo productions
hawaiki

[Roei Tzoref]

channel blur could work, but sometimes produces artifacts. another way is to try the refine soft matte effect, that could also produce artifacts. if all else fails, another way to go manually at it is to produce an edge matte. Vfx guru Mark Christiansen demonstrates that here: https://www.lynda.com/After-Effects-tutorials/Prevent-matte-clipping-Find-Edges-Minimax/114913/174524-4.html

Roei Tzoref
After Effects Artist & Instructor
♫ Ae Blues Tutorials

[Simon Ubsdell]

There are many different edge operations that require different processes. Pre-built processes are rarely the most useful answer.

Ultimately it pays to know all the many different techniques for building your own edge operations from scratch, but in this case we just don’t know that the OP is wanting to achieve.

Simon Ubsdell
tokyo productions
hawaiki

[Roei Tzoref]

thank you Simon and I agree. I meant to reply to Op.

always a good idea to show example of what you want to achieve to get a specific solution so Stig, feel free to show us in detail what the issue you want to resolve if the suggestion you got so far don’t get you there.

Roei Tzoref
After Effects Artist & Instructor
♫ Ae Blues Tutorials