title: how to find the points of the contour parts of the images using opencv python?
body: <p>I am trying to find the points of the contours parts(4 points) of the images (not related to the width and height of whole images).input image point are (0,0) (1300,0), (1800,0), and (1300,1800) and output image ( 0,0),(1300,0),(1600,0),(1300,1600) . My expected output should be for the bottom-left (100,1630) that mean  x will be start from  130.<br />
  my code is :</p>
  <pre><code>      contours, hierarcy=cv2.findContours(thresh_img, cv2.RETR_LIST, cv2.CHAIN_APPROX_SIMPLE)
        cv2.drawContours(original_img, contours, -1, (255,120,0), 2, cv2.LINE_AA)
        max_contours=max(contours, key=cv2.contourArea)
        x,y,w,g=cv2.boundingRect(max_contours)
        cv2.rectangle(original_img, (x,y), (x+w, y+h),(0.255,0),5)
        cropped_image1=original_img[y:y+h, x:x+w]
        plt.imshow(cropped_image1)
  </code></pre>
  <p>How to get this type of points of the images.I have used the getperspective transform (4 points transform )I do not get the expected result. Please tell me how to do ?
  Thanks....</p>