video stream needed for ARDRONE

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Hi,

This is Kathir. While using cv and ros bridge, I am not able to ardrone's camera's output in my computer. Could somebody help me to fix this ?

Should I have to change the topics in publisher or subscriber ? Why am I not getting the video feed ??

How to get video stream ? As per the code, imshow() should produce a window but in my code, nothing is happening.

#!/usr/bin/env python
import roslib
import sys
import rospy
import cv2
from std_msgs.msg import String
from sensor_msgs.msg import Image  
from cv_bridge import CvBridge, CvBridgeError

class image_converter:

 def __init__(self):
   print('Image converter constructor ')
   self.image_pub = rospy.Publisher("image_topic_2",Image,queue_size=1)

   self.bridge = CvBridge()
   self.image_sub = rospy.Subscriber("image_topic",Image,self.callback)

 def callback(self,data):
   try:
     cv_image = self.bridge.imgmsg_to_cv2(data, "bgr8")
   except CvBridgeError as e:
     print(e)

   (rows,cols,channels) = cv_image.shape
   if cols > 60 and rows > 60 :
     cv2.circle(cv_image, (50,50), 10, 255)
   print('Above imshow function')
   cv2.imshow("Image window", cv_image)
   cv2.waitKey(3)

   try:
     self.image_pub.publish(self.bridge.cv2_to_imgmsg(cv_image, "bgr8"))
   except CvBridgeError as e:
     print(e)


def main(args):
 ic = image_converter()
 print('inside main ')
 rospy.init_node('image_converter', anonymous=True)
 try:
   rospy.spin()
 except KeyboardInterrupt:
   print("Shutting down")
 cv2.destroyAllWindows()

 if __name__ == '__main__':
   print('Function call started ')
   main(sys.argv)

rostopic hz :

 rostopic hz /ardrone/image_raw
   subscribed to [/ardrone/image_raw]
   average rate: 31.109
      min: 0.011s max: 0.051s std dev: 0.00873s window: 31
   average rate: 31.077
      min: 0.011s max: 0.059s std dev: 0.00947s window: 62
   average rate: 30.875
      min: 0.011s max: 0.061s std dev: 0.00909s window: 92
   average rate: 30.508

rosgraph is :

/ardrone/image_raw/compressedDepth/set_parameters
  /ardrone_driver/set_logger_level
  /ardrone/front/image_raw/compressedDepth/set_parameters
  /ardrone/setledanimation
  /ardrone/image_raw/theora/set_parameters
  /image_converter_3034_1485929043890/set_logger_level
  /ardrone/front/image_raw/compressed/set_parameters
  /ardrone/front/set_camera_info
  /ardrone/setflightanimation
  /ardrone/setrecord
  /image_converter_3034_1485929043890/get_loggers
  /rosout/set_logger_level
  /ardrone/image_raw/compressed/set_parameters
  /ardrone_driver/get_loggers
  /ardrone/togglecam
  /ardrone/flattrim
  /ardrone/bottom/image_raw/theora/set_parameters
  /ardrone/bottom/set_camera_info
  /ardrone/bottom/image_raw/compressed/set_parameters
  /ardrone/bottom/image_raw/compressedDepth/set_parameters
  /rosout/get_loggers
  /ardrone/setcamchannel
  /ardrone/front/image_raw/theora/set_parameters