I would like to convert a scanned signature to a vector file. Specifically, I'd like to obtain a clean, small SVG, like Barack Obama's signature on Wikipedia. It consists solely of paths with no fill and a black stroke of width 1.4.
Here is an example scanned signature. I've tried the tracing functionality built into Inkscape 0.48 and Illustrator CS6 but was only able to obtain paths with anchors at the boundaries, plus fill and no stroke. Needless to say, the resulting SVG is not clean (path has varying width) and it's size is roughly four times that of the Obama signature.
Do any tools exist that can decently trace a scanned signature/line art as strokes, not as paths? If not, how would I go about creating the strokes manually with the pen tool in Illustrator?