Alternative to photoshop for editing colour/alpha channels?

[Debuk]

Affinity is a great and very affordable counterpart to PS: https://affinity.serif.com/
Beside that have a look here for other options:

Free or very affordable alternatives to Adobe tools

[image] Created by XDaniel on Twitter. As Audacity has lost some of its reputation lately, you might like to try Tenacity. And if you think GIMP is too user-unfriendly compared to Photoshop, you might like to check out PhotoGIMP, focused on providing a UI / UX similar to Photoshop. Also, I can heartily recommend Apple Motion as a powerful and very affordable alternative to After Effects for macOS users.