pnmpaste

Paste a PNM image into another PNM image. More information: https://netpbm.sourceforge.net/doc/pnmpaste.html.

pnmpaste x y path/to/image1.pnm path/to/image2.pnm > path/to/output.pnm

command | pnmpaste x y path/to/image.pnm > path/to/output.pnm

pnmpaste -and|nand|or|nor|xor|xnor x y path/to/image1.pnm path/to/image2.pnm > path/to/output.pnm