How to convert poor quality bitmap image to vector?

"I think there's also an open source solution for this, besides Adobe software: Inkscape

I've had the same problem a couple of years ago with a dozen of logos, and were able to solve it with Inkscape this way:

Open the bitmap image.
Left click on it to select it.
Path / Trace Bitmap
Now you have to start experimenting with the possible settings, and refreshing the preview on the right side of the dialog. ""Inkscape incorporates the Potrace program (http://potrace.sourceforge.net) to provide this functionality, and in-depth documentation about the function of this feature can be found at the web site for Potrace."" - from Inkscape documentation.
Save as SVG."

"The imagemagick Usage docs have a good explanation of how to perform edge detection and raster to vector conversion. From the edge_vector section, which begins by saying, essentially, for best results, don't use imagemagick:

Programs that can do this include: ""ScanFont"", ""CorelTrace"" and ""Streamline"" by Abobe. Most of these however cost a lot of money. But a free solution is ""AutoTrace"" or ""PoTrace"". Other suggestions are welcome.

Both trace programs are simple to use, but requires some pre and post image setup. They have a limited number of input formats, and outputs a vector image which will create a 'smoothed' form of the input image. I prefer the ""AutoTrace"" as it does not scale the resulting SVG, producing a standard line thickness, however you can not use it in a 'pipeline'.

For best results it is a good idea to ensure we only feed it a basic bitmap image, which we can ensure by thresholding the input image, while we convert it to a image format autotrace understands. I can then convert that image into a SVG vector image.

You can run autotrace online if you want to try it out."