ppmntsc
Make the RGB colors in a PPM image compatible with NTSC or PAL color systems.
TLDR
Make the RGB colors in a PPM image compatible with NTSC color systems
$ ppmntsc [path/to/input_file.ppm] > [path/to/output_file.ppm]
Make the RGB colors in a PPM image compatible with PAL color systems
$ ppmntsc --pal [path/to/input_file.ppm] > [path/to/output_file.ppm]
Print the number of illegal pixels in the input image to stderr
$ ppmntsc --verbose [path/to/input_file.ppm] > [path/to/output_file.ppm]
Output only legal/illegal/corrected pixels, set other pixels to black
$ ppmntsc --[legalonly|illegalonly|correctedonly] [path/to/input_file.ppm] > [path/to/output_file.ppm]