Calculating perimeter of an organic shape

I have used Python to calculate areas or irregular shapes on black and white images by multiplying the number of white pixels by the area of an individual pixel.

However, now I also need to calculate the perimeter of this irregular shape. The shape may have holes in it. Here is an example image:

Any ideas how I can go about solving this problem? I am not a complete newbie but I am not a coder either. Experienced beginner I guess.

Thanks in advance.

EDIT: There are some things I still don't understand but this worked for me:

import cv2
import numpy as np



def import_image(filename):
    original_image = cv2.imread(filename, cv2.IMREAD_UNCHANGED)
    return original_image

#getting original file
img = import_image('PerimeterImage.jpg')

#converting to gray
img_grey = cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)

#set a thresh
thresh = 1

#get threshold image
ret,thresh_img = cv2.threshold(img_grey, thresh, 255, cv2.THRESH_BINARY)

#find contours
image, contours, hierarchy = cv2.findContours(thresh_img, cv2.RETR_TREE, cv2.CHAIN_APPROX_SIMPLE)

#create an empty image for contours
img_contours = np.zeros(img.shape)

perimeter = 0

for c in contours:
    peri = cv2.arcLength(c, True)
    approx = cv2.approxPolyDP(c, 0.0001 * peri, True)
    cv2.drawContours(img_contours, [approx], -1, (0, 0, 255), 1)
    perimeter = perimeter + peri

print(f'Perimeter = {int(round(perimeter,0))} pixels')

#show image
cv2.imshow('Output', img_contours)
cv2.waitKey(0)

#save image
cv2.imwrite('contours.jpg', img_contours)