ppmhist
Print a histogram of the colors present in a PPM image.
TLDR
Generate the histogram for human reading
$ ppmhist -nomap [path/to/image_file.ppm]
Generate a PPM file of the colormap for the image, with the color histogram as comments
$ ppmhist -map [path/to/image_file.ppm]
Display version
$ ppmhist -version
