voronoiSkel uses only the pixel on the boundary of the objects, and therefore is very efficient for thick objects (efficiency scales with the object's radius, rather than its area). However, it might be sensitive to small defects, if they are on the boundaries (or small holes inside the object).
Also, the function analytically calculates the topology of the skeleton, and can give as an output the vertices and edges of the skeleton graph.
The function uses qhull (www.qhull.org, free download), and therefore qhull must be executable from the command line in the current directory. In order to enable that, you can either add qhull to your OS path, or keep a copy of it in the working directory.