title: DMatch Class Opencv
body: <p>I'm making a application that detects and recognizes an object on Android. With some research on the area I made the application and got some results, like this:
  <img src="https://i.stack.imgur.com/6uQvh.jpg" alt="enter image description here"></p>
  
  <p>However, I want to train my image, and I found on <strong>DMatch class</strong> that atributes <strong>trainIdx</strong> and <strong>queryIdx</strong> in the link below:</p>
  
  <p><a href="http://docs.opencv.org/java/org/opencv/features2d/DMatch.html" rel="nofollow noreferrer">OpenCV documentarion</a></p>
  
  <p>Can someone explain how can I use that on my application and the definition of those attributes ? 
  Thanks in advance.</p>