title: Image spot detection in Python
body: <p>I have millions of images containing every day photos. I'm trying to find a way to pick out those in which some certain colours are present, say, red and orange, disregarding the shape or object. The size may matter - e.g., at least 50x50 px.</p>
  
  <p>Is there an efficient and lightweight library for achieving this? I know there is OpenCV and it seems quite powerful, but would it be too bloated for this task? It's a relatively simple task, right?</p>
  
  <p>Thanks</p>