Apply a binary function on two Netpbm images. See also:
pamfunc. More information: https://netpbm.sourceforge.net/doc/pamarith.html.
pamarith -{{add|subtract|multiply|divide|difference|minimum|maximum|...}} {{path/to/image1.pam|pbm|pgm|ppm}} {{path/to/image2.pam|pbm|pgm|ppm}}