Android : Pictures in landscape mode on 1920x1200 tablets appear pressed

I want to place a picture in an app on tablet, with resolution 1920x1200 and the picture is the exact same size, but the problem is the software buttons on the bottom have some height and make the picture pressed on the top and bottom sides... How can I know whats the height of the software buttons, and do I have to manually cut every picture, or can I make it programatically? Or even better, can I just make somehow the picture take the whole screen, and the bottom end ot just go behind the software buttons?