canny_edge.py

#!/usr/bin/env python
from std_msgs.msg import Int32
import rospy, cv2, cv_bridge, numpy
from sensor_msgs.msg import Image
import cv2
import numpy as np
from matplotlib import pyplot as plt

class Follower:
	def __init__(self):
		self.bridge = cv_bridge.CvBridge()
		self.image_sub = rospy.Subscriber('/usb_cam/image_raw',Image, self.image_callback)
		#self.image_pub = rospy.Publisher('gray_image',Int32,queue_size=1)
	def image_callback(self, msg):
		image = self.bridge.imgmsg_to_cv2(msg)
		gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)				
		_, gray = cv2.threshold(gray, 130, 255, cv2.THRESH_BINARY)
		gaus = cv2.adaptiveThreshold(gray, 255, cv2.ADAPTIVE_THRESH_GAUSSIAN_C, cv2.THRESH_BINARY, 91, 12)
		mean_c = cv2.adaptiveThreshold(gray, 255, cv2.ADAPTIVE_THRESH_MEAN_C, cv2.THRESH_BINARY, 15, 12)
		cv2.imshow("window", gray )
		cv2.waitKey(3)
		#apply canny edge detection to the image
		edges = cv2.Canny(gray,50,150,apertureSize = 3)
		cv2.imshow("image_CANNY", edges)
		cv2.waitKey(3)
		lines = cv2.HoughLines(edges,1,np.pi/180,20)
		

rospy.init_node('follower')
follower = Follower()
rospy.spin()