AFNI program: 3dhistog

Compute histogram of 3D Dataset
Usage: 3dhistog [editing options] [histogram options] dataset

The editing options are the same as in 3dmerge.
The histogram options are:
  -nbin #   Means to use '#' bins (default = 100)
            Special Case: for short or byte dataset bricks,
                          set '#' to zero to have the number
                          of bins set by the brick range.
  -thr  r   Means to count only voxels with the statistics threshold above 'r'
  -dind i   Means to take data from sub-brick 'i'
  -tind j   Means to take threshold from sub-brick 'j'
  -omit x   Means to omit the value 'x' from the count.
  -notit    Means to leave the title line off the output.
  -mask m   Means to use the dataset 'm' to determine which voxels in the test
            dataset to include for the histogram

The histogram is written to stdout.

INPUT DATASET NAMES
-------------------
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'.