title: Check if image is black
body: <p>I'm running a Python script under Windows which deals with 480x800 <code>PNG</code> images with 32-bit depth. I need to check if the given image is fully black or not. After some searching I've found that ImageMagick could help me to achieve this but unfortunately there's no manual for such task.</p>
  
  <p>So a more general question is how to check if the image consists only of one color?</p>
  
  <p><strong>Edit:</strong></p>
  
  <p>My apologies for not providing all the information about the environment from beginning. The python script is executed using Android's <a href="http://developer.android.com/tools/help/monkeyrunner_concepts.html" rel="nofollow"><code>monkeyrunner</code></a>. Since it uses it's own instance of Jython (version 2.5) it's not possible to use any modules from external libraries. Inside there's a <code>MonkeyImage</code> class to work with screenshots taken from the device. So I adopted @eumiro's answer for it.</p>