pamdice

Slice a Netpbm image vertically or horizontally. See also: pamundice. More information: https://netpbm.sourceforge.net/doc/pamdice.html.

pamdice -outstem path/to/filename_stem -height value -width value path/to/input.ppm

pamdice -outstem path/to/filename_stem -height value -width value -hoverlap value -voverlap value path/to/input.ppm