Fun fact:
nostr.build uses sha256 to hash your image, and renames it that hash to prevent duplicate image uploads.
So although long, your image name is used the same hashing algorithm Bitcoin uses.
(a few of us are trying to come up with a better naming scheme, but this is it for now)
Ex.
nostr.build_bbb6694317ccaf24b3a7760097c8194f74fbcd2c932174d26373aae8c4c2a08f.jpeg