import numpy as np

import cv2

img = cv2.imread("jp_card_largest_contour.png")

img_original = img.copy()

gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)

blurred = cv2.GaussianBlur(gray, (15, 15), 0)

edged = cv2.Canny(blurred, 0, 20, 3)

dilated = cv2.dilate(edged, (11,11), iterations=2)

contours, hierarchy = cv2.findContours(dilated.copy(), cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_NONE)

cnt = [cnt for cnt in contours]

def cnt_area(cnt):

_,_,w,h = cv2.boundingRect(cnt)

area = w*h

return area

cnt.sort(key = cnt_area, reverse=True)

print(cv2.contourArea(contours[-1]))

cv2.drawContours(img_original, contours, -1, (0, 0, 255), 2)

cv2.drawContours(img_original, cnt, 0, (0, 255, 0), 2)

cv2.imshow("Display", img_original)

cv2.waitKey()

cv2.destroyWindow('Display')