I don't think this has to do anything with programming.
You can use inkscape, it's free. Depending on how complicated your image is the result is better or worse. Most likely you have to do some work by hand, but you get a vector image to start with.
I'm sure there are commercial programs that can get the job done, too. But don't know of any. Perhaps there is something useful in Adobe Photoshop or similar. I think they have a trial version somewhere.
Who needs a signature anyway.