potrace is a Peter Selinger's GPLed utility for tracing
bitmaps - converting them into smooth, scalable images.

It accepts as input a bitmap B/W images (PBM, PGM, PPM
and BMP formats), and returns encapsulated PostScript
(EPS) as the default output. Other output format are
available: PS, SVG, Xfig, PGM, PDF and experimental
GimpPath.

You can create scalable images from scans, such as
logos, hand taken notes, etc. The resulting smooth
images can then be rendered at any resolution.

WWW: http://potrace.sourceforge.net