This is the command ppmdim that can be run in the OnWorks free hosting provider using one of our multiple free online workstations such as Ubuntu Online, Fedora Online, Windows online emulator or MAC OS online emulator
ppmdim - dim a portable pixmap down to total blackness
ppmdim dimfactor [ppmfile]
Reads a portable pixmap as input. Diminishes its brightness by the specified dimfactor
down to total blackness. The dimfactor may be in the range from 0.0 (total blackness,
deep night, nada, null, nothing) to 1.0 (original picture's brightness).
As pnmgamma does not do the brightness correction in the way I wanted it, this small
program was written.
ppmdim is similar to ppmbrighten , but not exactly the same.
Use ppmdim online using onworks.net services