'Zoom Out' displays a larger area of the image. Together with Zoom-in, the magnification of the image may be varied from 1% to a value that depends on the amount of system-memory available. You may also rotate the mouse-wheel to zoom-out.
Resampling ON/OFF allows you to choose between speed and image quality when zooming.
The zoom value is displayed together with the Display Image Size.
(not shown on screenshots below)