Merry Christmas and Happy New Year 2013 to you.
I read this article and I found at the first time it is quite confusing.
I thought because of my English. Now I understand what you try to explain us how to do this.
So, I made a small tutorial how to do this since my friend asked for this.
This tutorial is step-by-step one. Explain all the process of how to obtain the photo and the information and how to calculate. Even you cannot read English, you can understand it by the pictures explain in side.
Best Wishes to you,