Finding center line of an image

I have this image after undergo canny edge detection using this function:

clear all; clc; a = imread('ddd.jpg'); b = rgb2gray(a); imshow(b); h = ones(7,7)/49; c = imfilter(b,h);

d = edge(c,'canny');

e = bwmorph(d, 'dilate') imshow(e)

Then, I want to find the center line of human body (human skeleton) of this filtered image. How am I supposed to do that? Is there any specific algorithm that I can use?

[Image Analyst]

To the computer, it's just a bunch of lines. It doesn't know which lines are part of a body unless you tell it. Heck, even I don't know for some of the lines. And I don't know what you mean by "center line" when the body is not shaped in a line.

[NURUL AMIRA MHD RIZAL]

actually this is the original image. I'm trying to get the human body skeleton.so that I can calculate the angle of certain parts of human joints.

[NURUL AMIRA MHD RIZAL]

similar to this one.