+3  A: 

When I built something similar I used this article quite a bit. But basically you're looking for the EXIF data embedded in the image.

There are a number of great libraries to extract it for you, if you don't want to write it from scratch.

Xenph Yan
+3  A: 

The following article should be helpful.

labilbe
+1  A: 

You probably want to use the BitmapMetadata class in the System.Windows.Media.Imaging namespace.

There is a BitmapMetadata sample that can be downloaded from MSDN.

spoon16
+1  A: 

Links to simliar StackOverflow questions: here, here and here.

Joel in Gö