VS 2010 - Extracting Text - Convert The English Text Shown In Screen To Malayalam

I'm trying to create a small program, which I think will be helpful to others(in here). My aim is to convert the English text shown in screen to Malayalam. English-to-Malayalam conversion is not a problem. But the problem is, how to extract the text from the screen. In most of the converter/translator, the text needs to be copied or written down in the translator tool. But my program will cut off that part. That is, simply move the program window (having a rectangle hollow portion) to the English word that needs to be converted. And upon pressing a button (or autodetect), the English word is converted to Malayalam.

So, my question is how to extract the English text(or words) from the screen (which is seen through the hollow portion of the window.

Here's a screenshot of what I'm trying to do.