Note that this reference documentation is identical to the help that is displayed in MATLAB when you type “help ft_defacevolume”.

  FT_DEFACEVOLUME allows you to de-identify an anatomical MRI by erasing specific
  regions, such as the face and ears. The graphical user interface allows you to
  position a box over the anatomical data inside which all anatomical voxel values will
  be replaced by zero. You might have to call this function multiple times when both
  face and ears need to be removed. Following defacing, you should check the result
  Use as
    mri = ft_defacevolume(cfg, mri)
  The configuration can contain the following options
    cfg.translate  = initial position of the center of the box (default = [0 0 0])
    cfg.scale      = initial size of the box along each dimension (default is automatic)
    cfg.translate  = initial rotation of the box (default = [0 0 0])
    cfg.selection  = which voxels to keep, can be 'inside' or 'outside' (default = 'outside')
    cfg.smooth     = 'no' or the FWHM of the gaussian kernel in voxels (default = 'no')
    cfg.keepbrain  = 'no' or 'yes', segment and retain the brain (default = 'no')   = 'no' or 'yes', whether to provide graphical feedback (default = 'no')
  If you specify no smoothing, the selected area will be zero-masked. If you
  specify a certain amount of smoothing (in voxels FWHM), the selected area will
  be replaced by a smoothed version of the data.