I see people asking an algorithm for skeletonization very frequently. At first, I had no idea about it. But today, I saw a blog which demonstrates simple method to do this. Code was in C++, so I would like to convert it to Python here.

What is Skeletonization?


Skeletonization using OpenCV-Python



Answer is just right in the term. Simply, it make a thick blob very thin, may be one pixel width. Visit the wikipedia page for more details : Topological Skeleton

Code : 

import cv2
	import numpy as np

	img = cv2.imread('sofsk.png',0)
	size = np.size(img)
	skel = np.zeros(img.shape,np.uint8)

	ret,img = cv2.threshold(img,127,255,0)
	element = cv2.getStructuringElement(cv2.MORPH_CROSS,(3,3))
	done = False

	while( not done):
	    eroded = cv2.erode(img,element)
	    temp = cv2.dilate(eroded,element)
	    temp = cv2.subtract(img,temp)
	    skel = cv2.bitwise_or(skel,temp)
	    img = eroded.copy()

	    zeros = size - cv2.countNonZero(img)
	    if zeros==size:
	        done = True

	cv2.imshow("skel",skel)
	cv2.waitKey(0)
	cv2.destroyAllWindows()
	

Below is the result I got:

Skeletonization using OpenCV-PythonSkeletonization using OpenCV-Python





References : 

1) http://felix.abecassis.me/2011/09/opencv-morphological-skeleton/