title: Change visual of histogram from image using matplotlib in Python
body: <p>I would like to present a histogram from an image in Python.
  Doing some research, I found a way of doing it using <a href="http://matplotlib.org/examples/pylab_examples/histogram_demo_extended.html" rel="nofollow noreferrer">matplotlib</a>. So, I just do this:</p>
  
  <pre><code>im = plt.array(Image.open('Mean.png').convert('L'))
  plt.figure()
  plt.hist(im, facecolor='green', alpha=0.75)
  plt.savefig("Histogram.png")
  </code></pre>
  
  <p>But I didn't like what I got:</p>
  
  <p><img src="https://i.stack.imgur.com/Xr8nU.png" alt="Histogram"></p>
  
  <p>The bars are not green, and it's kind of complicated to read the histogram. I could not even figure out if the x axis is the number of points and y axis the rgb color or the inverse... :S
  I would like to know if somebody knows how could I turn this histogram more readable. </p>
  
  <p>Thanks in advance.</p>