This is pretty sweet and easy. Not great, but good for some that don't have Photoshop, Corel Or Illustrator.
All of those have a tracing feature in it. (At least I think Corel does).
THese tracing features are more accurate and provide more control. It may take some adjustments to find the best results, but it's possible to get a FAR better or cleaner conversion. I uploaded one color jpg image and tried this out. It does give you some options down at the bottom to refine the conversion but for example, The exact same thing (and better) is done in Photoshop under IMAGE_ADJUSTMENTS and play with some of those features. Then copy/paste into a channel to clean it up even more.