How to do real time hand detection on Kinect V2/ROS

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I am very new to Kinect V2 and ROS Indigo. I have installed libfreenect2 and iai_kinect2 from the GitHub pages. After running rostopic list I get a list of topics published by Kinect. I wrote a small code so that it subscribes to a specific topic and displays the camera i.e image_mono

file.py:

#!/usr/bin/python

import roslib
import rospy
import cv2
import sys
from std_msgs.msg import String
from sensor_msgs.msg import Image
from cv_bridge import CvBridge, CvBridgeError

class PositionTracker:

    def __init__(self):
        # subscribe to kinect image messages
        self.sub = rospy.Subscriber("kinect2/qhd/image_mono", Image, self.image_callback, queue_size=1)
        self.bridge = CvBridge()

    def image_callback(self,data):
        try:
            cv_image = self.bridge.imgmsg_to_cv2(data)
        except CvBridgeError as e:
            print(e)
        cv2.imshow("Image window", cv_image)
        cv2.waitKey(3)

def main(args):
    ic = PositionTracker()
    rospy.init_node('kinect_tracker')
    try:
        rospy.spin()
    except KeyboardInterrupt:
        print("Shutting down")
    cv2.destroyAllWindows()

if __name__ == '__main__':
    main(sys.argv)

How do I perform real time hand detection and save data sets to a folder with the camera that was opened.

If I type, rostopic echo /kinect2/qhd/image_mono, it gives a 1D array. Any resource/tutorial will be really helpful.