title: ValueError: too many values to unpack (expected 3) using PIL
body: <p>I have an image of pixel size (1761, 460) and I am trying to find RGB values with Python using PIL. The image has 56 distinct colors in it. I am running the following code but I get an error saying:
  <code>ValueError: too many values to unpack (expected 3)</code></p>
  
  <p>Does anybody know a better method of doing this finding RGB values of an image?</p>
  
  <pre><code>  import numpy as np
    import matplotlib.pyplot as plt
    import colorsys
    from PIL import Image
  
    img_file=Image.open("orange 4.png")
    img = img_file.load()
    [xs, ys] = img_file.size
     for x in range(0, xs):
             for y in range(0, ys):
              [r, g, b] = img[x, y]
                r /= 255.0
                g /= 255.0
                b /= 255.0
  </code></pre>