cv2.connectedComponents not detecting components

Question

I am on Ubuntu, python 2.7. Working with OpenCV.

I was trying to understand exactly what the function cv2.connectedComponents is doing. This is the image:

Answer 1

This is because cv2.connectedComponents() considers only the white portion as a component. Hence you are getting a single component.

You have to invert your image. You can do so by using cv2.bitwise_not() function.

CODE:

import cv2
import numpy as np

img = cv2.imread('cc.png', 0)
ret, thresh = cv2.threshold(img, 127, 255, 0)

#---- Inverting the image here ----
img = cv2.bitwise_not(thresh)     
_, markers = cv2.connectedComponents(img)
print np.amax(markers)

RESULT:

19