title: Calculate percentage similarity of two images using OpenCV
body: <p>I am able to find matching features using bewlow shown code. I want to calculate percentage similarity between two images. I am new to OpenCV. Any kind of help will be highly appreciated.</p>
  
  <pre><code>    FeatureDetector detector = FeatureDetector.create(FeatureDetector.ORB);
      DescriptorExtractor extractor = DescriptorExtractor
              .create(DescriptorExtractor.ORB);
  
      detector.detect(image1, keypoints1);
      detector.detect(image2, keypoints2);
  
      extractor.compute(image1, keypoints1, descriptors1);
      extractor.compute(image2, keypoints2, descriptors2);
  
      DescriptorMatcher matcher = DescriptorMatcher
              .create(DescriptorMatcher.BRUTEFORCE_HAMMING);
  
      MatOfDMatch matches = new MatOfDMatch();
      matcher.match(descriptors1, descriptors2, matches);
  </code></pre>
  
  <p>Is there any other library available serving the same purpose?</p>