image detection

#!/usr/bin/env python

import rospy, cv2, cv_bridge
import numpy as np
from sensor_msgs.msg import	Image
from geometry_msgs.msg import Twist
from geometry_msgs.msg import PoseArray
from std_msgs.msg import Int32

class WayPoint:
	
	def __init__(self):

		rospy.init_node('ros_bridge')
		
		# Create a ROS Bridge
		self.ros_bridge = cv_bridge.CvBridge()

		# Subscribe to whycon image_out
		self.image_sub = rospy.Subscriber('whycon/image_out', Image, self.image_callback)


	def image_callback(self,msg):

		# 'image' is now an opencv frame
		# You can run opencv operations on 'image'

		###DETECTING COLOUR###
		image = self.ros_bridge.imgmsg_to_cv2(msg, desired_encoding='bgr8')
		blur3 = cv2.medianBlur(image,5)
		hsv = cv2.cvtColor(blur3,cv2.COLOR_BGR2HSV)
		image = self.ros_bridge.imgmsg_to_cv2(msg, desired_encoding='bgr8')
		blur3 = image
		hsv = cv2.cvtColor(blur3,cv2.COLOR_BGR2HSV)
		
		###DETECTING BLUE COLOUR##
		lower1 = np.array([110, 50, 50])
		upper1 = np.array([130, 255, 255])
		mask1 = cv2.inRange(hsv,lower1,upper1)
		res1 = cv2.bitwise_and(image,image,mask=mask1)
		blur1 = cv2.medianBlur(mask1,5)
		image1=blur3
		gray1 = cv2.cvtColor(res1,cv2.COLOR_BGR2GRAY)
		ret1,thresh1 = cv2.threshold(gray1,2,255,0)
		abc1, contours1, hierarchy1 = cv2.findContours(mask1,cv2.RETR_TREE,cv2.CHAIN_APPROX_SIMPLE)
		cv2.drawContours(res1,contours1,-1,(0,255,0),3) ##neglect 0
		print len(contours1)
		self.red=contours1

		##Detecting red colour##
		lower2 = np.array([0, 100, 100])
		upper2 = np.array([20, 255, 255])
		mask2 = cv2.inRange(hsv,lower2,upper2)
		res2 = cv2.bitwise_and(image,image,mask=mask2)
		blur2 = cv2.medianBlur(mask2,5)
		image2=blur2
		gray2 = cv2.cvtColor(res2,cv2.COLOR_BGR2GRAY)
		ret2,thresh2 = cv2.threshold(gray2,2,255,0)
		abc2, contours2, hierarchy2 = cv2.findContours(mask2,cv2.RETR_TREE,cv2.CHAIN_APPROX_SIMPLE)
		cv2.drawContours(res2,contours2,-1,(0,255,0),3) ##neglect 0
		print len(contours2)
		self.blue2=contours2


		##Detectingt the green colour
		lower = np.array([120, 100, 100])
		upper = np.array([145, 255, 255])
		mask = cv2.inRange(hsv,lower,upper)
		res = cv2.bitwise_and(image,image,mask=mask)
		blur3 = cv2.medianBlur(mask,5)
		image=blur3
		gray = cv2.cvtColor(res,cv2.COLOR_BGR2GRAY)
		ret,thresh = cv2.threshold(gray,2,255,0)
		abc, contours, hierarchy = cv2.findContours(mask,cv2.RETR_TREE,cv2.CHAIN_APPROX_SIMPLE)
		print len(contours)
		self.green=contours


		
if __name__ == '__main__':
	test = WayPoint()
	rospy.spin()