I've been lurking around here for quite some time now, but I realized it's time to ask a question of my own instead of looking for similar questions.
I have a light-colored image that I want to make a transparent background of without having any of the jagged white edges and whatnot, to make a signature and avatar and so on. I've tried the magic wand, Alpha Mask, and Alpha Space, none of which have succeeded. As I said, the image itself is very light (the attached image), so it's difficult to achieve what I'm trying to do.
Any suggestions or ideas?