AFNI program: 3dOverlap

Usage: 3dOverlap [options] dset1 dset2 ...
Output = count of number of voxels that are nonzero in ALL
         of the input dataset sub-bricks
The result is simply a number printed to stdout.  (If a single
brick was input, this is just the count of the number of nonzero
voxels in that brick.)
Options:
  -save ppp = Save the count of overlaps at each voxel into a
              dataset with prefix 'ppp' (properly thresholded,
              this could be used as a mask dataset).
Example:
  3dOverlap -save abcnum a+orig b+orig c+orig
  3dmaskave -mask 'abcnum+orig<3..3>' a+orig