Is an image mostly red or green?

red_vs_green.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-

import os, sys
from PIL import Image

def get_red_green_balance(filename):
  im = Image.open(filename)
  r, g = reduce(lambda c1, c2: [c1[0] + c2[0], c1[1] + c2[1]], im.getdata(), [0, 0])
  percent = (r + g) / 100.0
  return round(r / percent, 2), round(g / percent, 2) 

def main(path):
  if not os.path.exists(path):
    print "Path {} doesn't exist!".format(path)
    sys.exit() 
 
  table = "{:<31}{:<8}{:<8}"
  print table.format("File", "Red %", "Green %")
  print table.format("-" * 30, "-" * 7, "-" * 7)
  if os.path.isdir(path):
    for fname in [os.path.join(path, fn) for fn in next(os.walk(path))[2]]:
      r, g = get_red_green_balance(fname)
      print table.format(fname[:27] + "..." if len(fname) > 30 else fname, r, g)
  else:
    r, g = get_red_green_balance(path)
    print table.format(path[:30], r, g)

if __name__ == "__main__":
  main(sys.argv[1])