Actionscript 3.0 :: Capture A Jpeg In A Defined Part Of The Screen?

I am trying to reverse engineer this: [URL]

I have code to capture a jpg

The trouble is I cannot fugure out how to target the save to a specific part of the stage, as opposed to a screen shot.

here is the link:

[URL]

Hit the spacebar to save the jpeg.

Code: Select all//see com.adobe.images folder for information about downloading
//  the adobe JPGEncoder class
import com.adobe.images.JPGEncoder;
var rect:Sprite=new Sprite();

[Code].....