How can I automatically crop various kind of specific object?

What is the best way to crop a pattern automatically? This is the input image : http://ift.tt/2gpwEvK

And I need the result to be something like this :

http://ift.tt/2f9JN74

Is there any way to get rid of the unwanted feature around that object? I've tried using k-means, but since the color inside of the object is the same as the background, it didn't really work out perfectly. This is the result :

http://ift.tt/2gplqr9

http://ift.tt/2f9UoPr

Maybe there's a way to change the color of the unwanted part so that the k-means might be working? Any suggestion?