Using Workbench Command

DILATE A VOLUME FILE
   wb_command -volume-dilate
      <volume> - the volume to dilate
      <distance> - distance in mm to dilate
      <method> - dilation method to use
      <volume-out> - output - the output volume

      [-exponent] - use a different exponent in the weighting function
         <exponent> - exponent 'n' to use in (1 / (distance ^ n)) as the
            weighting function (default 7)

      [-bad-voxel-roi] - specify an roi of voxels to overwrite, rather than
         voxels with value zero
         <roi-volume> - volume file, positive values denote voxels to have
            their values replaced

      [-data-roi] - specify an roi of where there is data
         <roi-volume> - volume file, positive values denote voxels that have
            data

      [-subvolume] - select a single subvolume to dilate
         <subvol> - the subvolume number or name

      [-legacy-cutoff] - use the v1.3.2 method of excluding voxels further than
         the dilation distance when calculating the dilated value

      [-grad-extrapolate] - additionally use the gradient to extrapolate,
         intended to be used with WEIGHTED

         [-presmooth] - apply presmoothing before computing gradient vectors,
            not recommended
            <kernel> - the size of gaussian smoothing kernel in mm, as sigma by
               default

            [-fwhm] - kernel size is FWHM, not sigma

      For all voxels that are designated as bad, if they neighbor a non-bad
      voxel with data or are within the specified distance of such a voxel,
      replace the value in the bad voxel with a value calculated from nearby
      non-bad voxels that have data, otherwise set the value to zero.  No
      matter how small <distance> is, dilation will always use at least the
      face neighbor voxels.

      By default, voxels that have data with the value 0 are bad, specify
      -bad-voxel-roi to only count voxels as bad if they are selected by the
      roi.  If -data-roi is not specified, all voxels are assumed to have data.

      To get the behavior of version 1.3.2 or earlier, use '-legacy-cutoff
      -exponent 2'.

      Valid values for <method> are:

      NEAREST - use the value from the nearest good voxel
      WEIGHTED - use a weighted average based on distance