title: Feature detection - Small item in a large picture
body: <p>Assume you have two images. In one you have a small icon (like less than 300X300 pixels). The second is a very large one, and in within you have one (or multiple) smaller instances of the icon (of course at different scale, rotation). </p>
  
  <p>The task at hand is to find the instances of the icon in the big image. How would you guys approach this? </p>
  
  <p>I've tried to use a feature based object detection, by using the OpenCV library, however for crowded big images (containing many feature points), the matching is inconclusive. I've tried the SURF/OBJ feature extractors with the BRUTE/FLAN matching algorithms. </p>
  
  <p>From my experience it seems like the matching takes no note of the geometrical relations between the feature points on the two images. As a visualization help I've attached an instance of the feature points of two example images. <img src="https://i.stack.imgur.com/nD2S8.png" alt="enter image description here"></p>
  
  <p>And here's a harder instance of the task. I've highlighted the icon in the big image. <img src="https://i.stack.imgur.com/maEnq.jpg" alt="enter image description here"></p>