Automatic backlight control for ubuntu

autoSetBacklight.py

import os, time
import pyscreenshot as ImageGrab

while True:
    screen = ImageGrab.grab()
    dark = 0
    bright = 0
    
    for i in screen.getdata():
        if i[0] > 150 and i[1] > 150 and i[2] > 150:
            bright += 1
        else:
            dark += 1
    
    # calc backlight percent        
    percent = 100 - (bright * 100) / (bright + dark)
    
    print "Resolution", screen.size[0], 'x', screen.size[1], " -> setBacklight: %", percent
    # set backlight
    os.system("xbacklight -set %d"%percent)
    
    time.sleep(3)