Usage: 3dRank [-prefix PREFIX] <-input DATASET1 [DATASET2 ...]>

Replaces voxel values by their rank in the set of
values collected over all voxels in all input datasets
If you input one dataset, the output should be identical
to the -1rank option in 3dmerge

This program only works on datasets of integral storage type,
and on integral valued data stored as floats.

  -input DATASET1 [DATASET2 ...]: Input datasets.
                                  Acceptable data types are:
                                  byte, short, and floats.
  -prefix PREFIX: Ouput prefix.
                  If you have multiple datasets on input
                  the prefix is preceded by r00., r01., etc.
                  If no prefix is given, the default is
                  rank.DATASET1, rank.DATASET2, etc.

                  In addition to the ranked volume, a rank map
                  1D file is created. It shows the mapping from
                  the rank (1st column) to the integral values
                  (2nd column) in the input dataset. Sub-brick float
                  factors are ignored.

  -ver = print author and version info
  -help = print this help screen

This program accepts datasets that are modified on input according to the
following schemes:
  'r1+orig[3..5]'                                    {sub-brick selector}
  'r1+orig<100..200>'                                {sub-range selector}
  'r1+orig[3..5]<100..200>'                          {both selectors}
  '3dcalc( -a r1+orig -b r2+orig -expr 0.5*(a+b) )'  {calculation}
For the gruesome details, see the output of 'afni -help'.

++ Compile date = Aug 10 2020 {AFNI_20.2.11:linux_ubuntu_16_64}