Recognize open and closed shapes opencv

Question

how to detect open and closed shapes in opencv.

These are simple sampl

Answer 1

Python implementation of the same as below.

import cv2


src = cv2.imread('test.png', cv2.IMREAD_COLOR)

#Transform source image to gray if it is not already
if len(src.shape) != 2:
    gray = cv2.cvtColor(src, cv2.COLOR_BGR2GRAY)
else:
    gray = src

ret, thresh = cv2.threshold(gray, 200, 255, cv2.THRESH_BINARY_INV)
contours, hierarchy = cv2.findContours(thresh, cv2.RETR_CCOMP, cv2.CHAIN_APPROX_SIMPLE)
hierarchy = hierarchy[0]

for i, c in enumerate(contours):
    if hierarchy[i][2] < 0 and hierarchy[i][3] < 0:
        cv2.drawContours(src, contours, i, (0, 0, 255), 2)
    else:
        cv2.drawContours(src, contours, i, (0, 255, 0), 2)
#write to the same directory
cv2.imwrite("result.png", src)