Canny Edge detection

import cv2
import numpy as np
import matplotlib.pyplot as plt

def passfunc(nothing):
    pass


cv2.namedWindow("img",cv2.WINDOW_NORMAL)
cv2.resizeWindow("img",1080,720)
img = cv2.imread("map.png")

plt.imshow(img[:,:,::-1])
plt.show()

img = cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)
plt.imshow(img)
plt.show()

blur_img = cv2.GaussianBlur(img,(5,5),0)
plt.imshow(blur_img)
plt.show()

edge_img = cv2.Canny(img,50,200)

cv2.createTrackbar("t1","img",0,1000,passfunc)
cv2.createTrackbar("t2","img",0,1000,passfunc)

while(1):
    
    cv2.imshow("img",edge_img)
    
    
    
    k = cv2.waitKey(1) & 0XFF
    
    if k==27:
        break
    
    t1 = cv2.getTrackbarPos("t1","img")
    t2 = cv2.getTrackbarPos("t2","img")
    
    edge_img = cv2.Canny(img,t1,t2)
    
    
    
    
cv2.destroyAllWindows()