pamfunc

Apply a simple arithmetic function to a Netpbm image. More information: https://netpbm.sourceforge.net/doc/pamfunc.html.

pamfunc -multiplier|divisor|adder|subtractor|min|max n path/to/input.pam > path/to/output.pam

pamfunc -andmask|ormask|xormask|shiftleft|shiftright n path/to/input.pam > path/to/output.pam