title: TypeError: integer argument expected, got float when converting an image to greyscale
body: <p>I am using the following code to convert a color image to a grayscale image. Why does it throw a <code>TypeError</code>?</p>
  
  <pre><code>#!/usr/bin/python
  from PIL import Image
  im = Image.open("Penguins.jpg")
  pixel = im.load()
  width, height = im.size
  for x in range(width):
      for y in range(height):
          R,G,B = pixel[x,y]
          pixel[x,y] = ((0.299*R+0.587*G+0.114*B),(0.299*R+0.587*G+0.114*B),(0.299*R+0.587*G+0.114*B))
  
  im.save("Penguins_new.jpg")
  </code></pre>