Ros-opencv after few computations cannot see the image

edit

Hi ,

So i'm trying to detect lines with turtlebot via kinect rgb camera. Everything was working until i added cv2.HoughLinesP() i think it still works but image window comes up as menubar only :) canny and gaussianblur works fine with a bit latency but at least i can see the image

i tried to add rospy.sleep() . im not sure where to go from this point. any suggestions?

thanks

def __init__(self):
    rospy.init_node('test_node')
    self.bridge=CvBridge()

    self.image_sub = rospy.Subscriber("/camera/rgb/image_color", Image, self.callback)

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

    cv_image=(255-cv_image)

    g_img=cv2.cvtColor(cv_image,cv2.COLOR_BGR2GRAY)
    g_img=cv2.GaussianBlur(g_img,(5,5),200)
    thresh=cv2.Canny(g_img,5,150,5)
    lines = cv2.HoughLinesP(thresh,2,np.pi/180,100,100,1)
    print lines.shape
    for i in range(0,lines.shape[0]):
        for x1,y1,x2,y2 in lines[i]:
            cv2.line(cv_image,(x1,y1),(x2,y2),(0,255,0),2)

    cv2.imshow("image",lines)
    cv2.waitKey(3)
    #rospy.sleep(10)