gistfile1.py

#! /usr/bin/python
import Image


source = Image.open("test.jpg")
img = source.load()

width = source.size[0]
height = source.size[1]

for y in xrange(0, height):
  for x in xrange(0, width):
		img[x, y] = (255 - img[x,y][0], 255 - img[x,y][1], 255 - img[x,y][2],)
	
source.save("danify.png")