ppmchange

Change all pixels of one color in a PPM image to another color. More information: https://netpbm.sourceforge.net/doc/ppmchange.html.

• Exchange the first color in each oldcolor - newcolor pair with the second color:

ppmchange oldcolor1 newcolor1 oldcolor2 newcolor2 … path/to/input.ppm > path/to/output.ppm

• Specify how similar colors must be in order to be considered the same:

ppmchange -closeness percentage oldcolor1 newcolor1 oldcolor2 newcolor2 … path/to/input.ppm > path/to/output.ppm

• Replace all pixels not specified in the arguments by a color:

ppmchange -remainder color oldcolor1 newcolor1 oldcolor2 newcolor2 … path/to/input.ppm > path/to/output.ppm