Contour changing using trackbar in python(Open cv , image processing)

Sorry video is lagging at the time of changing the contours due to weak processor.

Code:

import cv2
import numpy as np

#Initialising callback function of trackbar
def nothing(x):
pass

#Contour detection after smoothing the image
img_location = input('Enter image location:\n')
img = cv2.imread(img_location,-1)
blur = cv2.blur(img,(3,3))
im_gray = cv2.cvtColor(blur,cv2.COLOR_BGR2GRAY)
ret, thresh = cv2.threshold(im_gray,0,255,cv2.THRESH_BINARY+cv2.THRESH_OTSU)
_,contours,_ = cv2.findContours(thresh,cv2.RETR_LIST,cv2.CHAIN_APPROX_SIMPLE)

#Creating window
cv2.namedWindow('Contours',cv2.WINDOW_NORMAL)

#Creating Trackbar
cv2.createTrackbar('Trackbar','Contours',0,len(contours)-1,nothing)

#Creating dictionary of perimeter of the contours
contoursDict,indice = {},0
for cnt in contours:
perimeter = cv2.arcLength(cnt,True)
contoursDict[indice] = perimeter
indice += 1

#Making a contour having contours in ascending order
acs_contours = []
for item in sorted(contoursDict.items(),key = lambda x: x[1],reverse = False):
acs_contours.append(contours[item[0]])

#Final loop
while True:

#getting Trackbar position
position = cv2.getTrackbarPos('Trackbar','Contours')

#For making the image contour free when position changes
blur = cv2.blur(img,(3,3))

#Drawing contours of Red color with 3 pixel thickness
cv2.drawContours(blur,acs_contours,position,(0,0,255),3)
cv2.imshow('Contours',blur)

#Press 'q' to quit the program
if cv2.waitKey(1) == ord('q'):
break

cv2.destroyAllWindows()