title: Display an image over another image at a particular co-ordinates in openCV
body: <p>I am trying to display an image over another image at a particular co-ordinates. I have detected the aruco markers using the webcam and I want to display another image over the aruco marker. The aruco marker can be moved and the overlaying image should move along with the marker.</p>
  
  <p>There is various draw functions and to input text into the image. I have tried image overlay and image homography.</p>
  
  <p>I can obtain the co-ordinates for the corners.
  Is there any function to insert the image at those co-ordinates?</p>
  
  <pre><code>import cv2
  import cv2.aruco as aruco
  import glob
  
  markerLength = 0.25
  
  cap = cv2.VideoCapture(0)
  
  criteria = (cv2.TERM_CRITERIA_EPS + cv2.TERM_CRITERIA_MAX_ITER, 30, 0.001)
  
  objp = np.zeros((6*7,3), np.float32)
  objp[:,:2] = np.mgrid[0:7,0:6].T.reshape(-1,2)
  
  objpoints = [] 
  imgpoints = []
  
  images = glob.glob('calib_images/*.jpg')
  
  for fname in images:
      img = cv2.imread(fname)
      gray = cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)
  
      ret, corners = cv2.findChessboardCorners(gray, (7,6),None)
  
      if ret == True:
          objpoints.append(objp)
  
          corners2 = cv2.cornerSubPix(gray,corners,(11,11),(-1,-1),criteria)
          imgpoints.append(corners2)
          img = cv2.drawChessboardCorners(img, (7,6), corners2,ret)
  
  
  ret, mtx, dist, rvecs, tvecs = cv2.calibrateCamera(objpoints, imgpoints, gray.shape[::-1],None,None)
  
  calibrationFile = "calibrationFileName.xml"
  calibrationParams = cv2.FileStorage(calibrationFile, cv2.FILE_STORAGE_READ) 
  camera_matrix = calibrationParams.getNode("cameraMatrix").mat() 
  dist_coeffs = calibrationParams.getNode("distCoeffs").mat() 
  
  while(True):
      ret, frame = cap.read()
  
      gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
      aruco_dict = aruco.Dictionary_get(aruco.DICT_6X6_250)
      arucoParameters =  aruco.DetectorParameters_create()
  
      corners, ids, rejectedImgPoints = aruco.detectMarkers(gray, aruco_dict, parameters=arucoParameters)
      if np.all(ids != None):
          rvec, tvec, _ = aruco.estimatePoseSingleMarkers(corners, markerLength, mtx, dist) 
          axis = aruco.drawAxis(frame, mtx, dist, rvec, tvec, 0.3) 
          print(ids)
          display = aruco.drawDetectedMarkers(axis, corners)
          display = np.array(display)
      else:
          display = frame
  
      cv2.imshow('Display',display)
      if cv2.waitKey(1) &amp; 0xFF == ord('q'):
              break
  
  cap.release()
  cv2.destroyAllWindows()```
  </code></pre>