how to get absolute X/Y coordinates for a display object nested within Display Groups in Corona?

For fault finding, how can I print out the Absolute co-ordinates of a display object (e.g. image) that is buried within Display Groups? (i.e. don't want the relative position) That is position relative to the actual display resolution, so say: Xleft, Xright, Ytop, Ybottom co-ordinates type thing.