Contours

Contours is a python list of all the contours in the image. Each individual contour is a numpy array of (x,y) coordinates of boundary points of the object.

import numpy as np
import cv2

img = cv2.imread('opencv-logo.png')
imgray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
ret, thresh = cv2.threshold(imgray, 127, 255, 0)
contours, hierarchy = cv2.findContours(thresh, cv2.RETR_TREE, cv2.CHAIN_APPROX_NONE)
print("Number of contours = "+str(len(contours)))
print(contours[0])


cv2.drawContours(img, contours, 4, (0, 255, 0), 3)
#we can change the parameter -1(draw all contours) to 0to8 because the total contours is 9.

cv2.imshow('Image', img)
cv2.imshow('Image GRAY', imgray)
cv2.waitKey(0)
cv2.destroyAllWindows()