pnmindex

Build a visual index of multiple PNM images. See also: pamundice. More information: https://netpbm.sourceforge.net/doc/pnmindex.html.

pnmindex path/to/input1.pnm path/to/input2.pnm ... > path/to/output.pnm

pnmindex -size 50 path/to/input1.pnm path/to/input2.pnm ... > path/to/output.pnm

pnmindex -across 10 path/to/input1.pnm path/to/input2.pnm ... > path/to/output.pnm

pnmindex -colors 512 path/to/input1.pnm path/to/input2.pnm ... > path/to/output.pnm