find_intersection.py

import cv2

# find intersection percentage between to images
def find_intersection_percent(im1_path, im2_path):
    im1 = cv2.imread(im1_path, cv2.IMREAD_UNCHANGED)
    _, mask1 = cv2.threshold(im1[:, :, 3], 1, 255, cv2.THRESH_BINARY)
    cv2.imwrite('im1-mask.png', mask1)

    im2 = cv2.imread(im2_path, cv2.IMREAD_UNCHANGED)
    _, mask2 = cv2.threshold(im2[:, :, 3], 1, 255, cv2.THRESH_BINARY)
    cv2.imwrite('im2-mask.png', mask2)

    intersection = cv2.bitwise_and(mask1, mask2)
    intersection_area = cv2.countNonZero(intersection)
    intersection_area_percent = intersection_area / (mask1.shape[0] * mask1.shape[1])
    intersection_area_percent = intersection_area_percent * 100
    return intersection_area_percent

result = find_intersection_percent(
    '../layers-prepared/Accessories/Black glasses#1000000.png', 
    '../layers-prepared/Clothes/Army vest#300000.png')

# print result
print(result)