User blog comment:Mikemacdee/goodreads sample chapter/@comment-26030957-20160510165432/@comment-4715955-20160512232519

That's what I meant: it's a jpg, so it looks like shit.

They have a file size limit to uploads for one reason or another, but the actual size is an issue too, because if the thing is too small it'll look too pixelly, and they warn you about this. So either your png is too big and won't be accepted, or it's too small and looks low-quality.

Didn't try with tiffs yet.