How to view Full Size Profile Picture

Facebook provided a security feature which hides full size profile picture image from anyone else other than friends, it can also be possible to hide it from friends by changing privacy to 'Only Me'.
Most of the time it's not easy to recognize the profile picture due to the small size of the box which is 160 x 160. So, How to grasp full size profile picture ?

If you're use to firefox addons and chrome webstore, there are lots of browser apps that automate your work to view hidden profile pictures.

Firefox:  Facebook Profile Picture Revealer
Chrome: Facebook Full-Size Profile Pictures

You need to only install this apps and they work well without any sound.
If you're not comfortable with above trick than you can use this manual method which doesn't need any app installation in your browser.

Update (14th Dec, '14)

1. Open Profile Page whose Profile Picture, you want to reveal.

2. Copy the URL of the Profile Page and paste on this page.

Steps to view full size Profile Picture manually ( not valid )

1. Open Profile whose Profile Picture, you want to reveal.
2. Right click on Profile Picture and click on View Image/Open image in new tab. You see something like this in URL bar.

https://fbcdn-profile-a.akamaihd.net/hprofile-ak-xfa1/t1.0-1/c22.22.274.274/s160x160/374336_138451796315603_1773437540_n.jpg 

3. You need to remove red code from the above url and open that url. URL will be like this after removing red code.

https://fbcdn-profile-a.akamaihd.net/374336_138451796315603_1773437540_n.jpg

4. It's done.