pamarith
Apply a binary function on two Netpbm images.
TLDR
Apply the specified binary function pixel-wise on the two specified images (which must be of the same size)
$ pamarith -[add|subtract|multiply|divide|difference|minimum|maximum|...] [path/to/image1.pam|pbm|pgm|ppm] [path/to/image2.pam|pbm|pgm|ppm]
