Shapes Detection OpenCV & Python

# importing the library OpenCV
import cv2

# reading image
img = cv2.imread('shapes.png')
  
# converting image into grayscale image
gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
  
# setting threshold of gray image
_, threshold = cv2.threshold(gray, 127, 255, cv2.THRESH_BINARY)
  
# using a findContours() function
contours, _ = cv2.findContours(
    threshold, cv2.RETR_TREE, cv2.CHAIN_APPROX_SIMPLE)
  
i = 0
  
# list for storing names of shapes
for contour in contours:
  
    # here we are ignoring first counter because 
    # findcontour function detects whole image as shape
    if i == 0:
        i = 1
        continue
  
    # cv2.approxPloyDP() function to approximate the shape
    approx = cv2.approxPolyDP(
        contour, 0.01 * cv2.arcLength(contour, True), True)
      
    # using drawContours() function 
    cv2.drawContours(img, [contour], 0, (60, 20, 220), 5)
  
    # finding center point of shape
    M = cv2.moments(contour)
    if M['m00'] != 0.0:
        x = int(M['m10']/M['m00'])
        y = int(M['m01']/M['m00'])
  
    # putting shape name at center of each shape
    if len(approx) == 3:
        cv2.putText(img, 'Triangle', (x, y),
                    cv2.FONT_HERSHEY_SIMPLEX, 0.8, (0, 0, 0), 2)
  
    elif len(approx) == 4:
        cv2.putText(img, 'Quadrilateral', (x, y),
                    cv2.FONT_HERSHEY_SIMPLEX, 0.8, (0, 0, 0), 2)
  
    elif len(approx) == 5:
        cv2.putText(img, 'Pentagon', (x, y),
                    cv2.FONT_HERSHEY_SIMPLEX, 0.8, (0, 0, 0), 2)
  
    elif len(approx) == 6:
        cv2.putText(img, 'Hexagon', (x, y),
                    cv2.FONT_HERSHEY_SIMPLEX, 0.8, (0, 0, 0), 2)

    elif len(approx) == 10:
            cv2.putText(img, 'Star', (x, y),
                        cv2.FONT_HERSHEY_SIMPLEX, 0.8, (0, 0, 0), 2)
    else:
        cv2.putText(img, 'circle', (x, y),
                    cv2.FONT_HERSHEY_SIMPLEX, 0.8, (0, 0, 0), 2)
  
# displaying the image after drawing contours
cv2.imshow('shapes', img)
cv2.imwrite('detected_shapes.png', img)
# cv2.waitKey(0)
# cv2.destroyAllWindows()