AFNI program: 3dRowFillin

Usage: 3dRowFillin [options] dataset
Extracts 1D rows in the given direction from a 3D dataset,
searches for blank (zero) regions, and fills them in if
the blank region isn't too large and it is flanked by
the same value on either edge.  For example:
     input row = 0 1 2 0 0 2 3 0 3 0 0 4 0
    output row = 0 1 2 2 2 2 3 3 3 0 0 4 0

OPTIONS:
 -maxgap N  = set the maximum length of a blank region that
                will be filled in to 'N' [default=9].
 -dir D     = set the direction of fill to 'D', which can
                be one of the following:
                  A-P, P-A, I-S, S-I, L-R, R-L, x, y, z
                The first 6 are anatomical directions;
                the last 3 are reference to the dataset
                internal axes [no default value].
 -prefix P  = set the prefix to 'P' for the output dataset.

N.B.: If the input dataset has more than one sub-brick,
      only the first one will be processed.

The intention of this program is to let you fill in slice gaps
made when drawing ROIs with the 'Draw Dataset' plugin.  If you
draw every 5th coronal slice, say, then you could fill in using
  3dRowFillin -maxgap 4 -dir A-P -prefix fredfill fred+orig