The fully automated process consists of three steps:
  1- Preprocessing of volume to remove gross spatial image 
  non-uniformity artifacts and reposition the brain in
  a reasonable manner for convenience.
    ** Note that in many cases, using 3dUnifize before **
    ** using 3dSkullStrip will give better results.    **
  2- Expand a spherical surface iteratively until it envelopes
  the brain. This is a modified version of the BET algorithm:
     Fast robust automated brain extraction, 
      by Stephen M. Smith, HBM 2002 v 17:3 pp 143-155
    Modifications include the use of:
     . outer brain surface
     . expansion driven by data inside and outside the surface
     . avoidance of eyes and ventricles
     . a set of operations to avoid the clipping of certain brain
       areas and reduce leakage into the skull in heavily shaded
       data
     . two additional processing stages to ensure convergence and
       reduction of clipped areas.
     . use of 3d edge detection, see Deriche and Monga references
       in 3dedge3 -help.
  3- The creation of various masks and surfaces modeling brain
     and portions of the skull