you mean to not have to trace it by hand?
You can try a bitmap trace with Inkscape inkscape.org, save the svg, then import the svg path file.
Just tried it from a previous svg file (not a traced one) and it worked as expected.
Hi Spin! You might be interested to look at another open source project http://autotrace.sourceforge.net/ Haven’t used it myself but if it’s anything like Flashes Trace bitmap - it’s only going to do half the job. Worth a peek though
You can also create Meshes from Textures in Blender by using the Noise button - but you Mesh must be sub-divided enough to have an effect. Most extrusions from this feature look like 3D pixels… /Edit
I wrote a displacement script in Maya to create a very basic cave. I used the grayscale values to determin the height of each vertex in the mesh, the whiter the pixel, the higher the vertex.