ros capture image

#!/usr/bin/env python
import rospy
from sensor_msgs.msg import Image
import numpy as np
import cv2
from cv_bridge import CvBridge

class CaptureImage(object):
    def __init__(self):
        self.sub_img = rospy.Subscriber("/camera/projected_image", Image, self.get_img)
        self.cvbridge = CvBridge()
        self.num = 12

    def get_img(self, img):
        cv_img = self.cvbridge.imgmsg_to_cv2(img, "bgr8")
        print("cv_img shape", cv_img.shape)
        cv2.imshow("img", cv_img)
        key = cv2.waitKey(33)
        
        if key == 97:
            print("capture image")
            cv2.imwrite("./images/"+str(self.num)+".jpg", cv_img)
            self.num += 1

    def spin(self):
        rospy.spin()

if __name__ == "__main__":
    rospy.init_node("test")
    CaptureImage().spin()