title: How to determine a region of interest and then crop an image using OpenCV c++
body: <p>I have a sample image as below. I would like to make the  square my Region of Interest and then crop out that part (square) and create a new image with it. I will be working with different images so the square won't always be at the same location in all images. So I will need to somehow detect the edges of the square.</p>
  
  <p>I can not post pictures because I have 10 reputations</p>
  
  <p>help me please??</p>
  
  <p>Thank you very much</p>