visit the link:

http://naveenideas.blogspot.in/2016/02/matlab-cropping-binary-image-algorithm.html

http://naveenideas.blogspot.in/2016/02/matlab-cropping-binary-image-algorithm.html

https://en.wikipedia.org/wiki/Minimum_bounding_box

If all images that you want to process as the image on the site you can use the following function in Matlab, just pass your BW image and you will get a cropped image that contains just the object of interest without the background.

function final=crop(bwim)

img=bwim;

[x,y]=find(img>0);

maxy=max(y);

maxx=max(x);

miny=min(y);

minx=min(x);

final=img(minx:maxx,miny:maxy);

regards

Hello Dear 

I have to say to you there are different if you extract object or you extract human skin

 http://www.mathworks.com/help/images/ref/activecontour.html

http://clickdamage.com/sourcecode/index.php

the best way is to :

vh=sum(im);hh=sum(im');

vht=vh>threshold;hht=hh>threshold;

[x]=find(vht>0);

[y]=find(hht>0);

maxy=max(y);

maxx=max(x);

miny=min(y);

minx=min(x);

final=img(minx:maxx,miny:maxy);

Hope to be usefull

How can we decide the vht and hht?