>>42607283>>42607649Color-to-Alpha in GIMP does a decent job on single-color backgrounds.
Double-check the result on a pure black background afterwards. If you don't see any leftover white pixels and the image itself doesn't look "rough" around the edges, then you're good to go.
Protip:
Increasing the selection by 1px after a single click with the Fuzzy tool usually separates the image from the background *just* right. 