ppmtorgb3
Separate the color components of a PPM file into three separate PGM files.
See also: rgb3toppm.
More information: https://netpbm.sourceforge.net/doc/ppmtorgb3.html.
- Separate the color components of a PPM file, saving the outputs to
file.red,file.grnandfile.blu:
ppmtorgb3 path/to/file.ppm