title: How to count objects in image using python?
body: <p>I am trying to count the number of drops in this image and the coverage percentage of the area covered by those drops.
  I tried to convert this image into black and white, but the center color of those drops seems too similar to the background. So I only got something like the second picture. 
  Is there any way to solve this problem or any better ideas?
  Thanks a lot.</p>
  
  <p><img src="https://i.stack.imgur.com/ba3g0.jpg" alt="source image"></p>
  
  <p><img src="https://i.stack.imgur.com/xG91h.jpg" alt="converted image"></p>