Is the Galaxy S2 also known as the GT-19000?
If so, it tells you how to do this in the manual.
You could try reading it. You never know, you might just find other useful things in it.
http://downloadcenter...1.7_120314_Screen.pdf
Thanks for you useful contribution Michael. When I am back home i will be able to look at the manual. I must remember to look at how many questions you have asked that you could have googled the answers for whilst i am at it