Inkscape to trace bitmap with 4k+ colors

Question

I'm trying to convert (trace) this image to an svg file:

Full size Image

I run Path > Trace Bitmap, 256 colors, no smooth, no stack, remove bg, no optimize paths. It vectorizes ok but the colors are changed slightly, which can't happen, since the rgb of the fill is essentially the ID of the shape, which means I can't map from svg -> the webpage.

It won't let me go over 256 colors either, and there's roughly 4k+. Is there a way around this limit, or is there another program I can also use?

Edit: The problem isn't so much the tracing, but the specific colours:

province red green blue x hex 0 1 128 34 64 Stockholm #802240 1 2 0 36 128 Östergötland #002480 2 3 128 38 192 Småland #8026c0

On my resulting images, those hex colours don't match to the ones I have on file (and what they are on the original .bmp)

Answer 1

AFAIK the vectorization process in inkscape is just a color quantization + n call to potrace. I guess the color reduction first stage is done using median-cut algorithm which is prone to color quantization error.

So I think you won't be able to preserve the colors while tracing in inkscape.

Maybe you could try the script @ http://www.inkscapeforum.com/viewtopic.php?t=30972

which is a shell script that uses imagemagick to sort the colors by area in your image and then launch a potrace on a mask for every color then combine the n svgs.