VS3D can perform engraving/milling from "raster" images (MP, TIF, JPEG, etc.).
Here is an example of doing V-bit carving of a logo from a raster image:
http://www.designscomputed.com/vs3d/...ext_carve.html
I think this is very similar to what you want to do.
You can also perform 3D ("grayscale") image embossing/carving. Here is an example of that:
http://www.designscomputed.com/vs3d/...mg_emboss.html