Mouse Wheel

Turn the Mouse Wheel while optionally holding down modifier keys

The image in the Preview Viewport can be zoomed and scrolled through the use of a Mouse Wheel.

Scroll

Turning the Mouse Wheel with no modifier keys scrolls the image up or down.

Holding down the Control key scrolls the image right or left.
Adding the Shift key causes the scroll distance to be increased to one screen width or height at a time.

Turning the Mouse Wheel while holding down the Alt key zooms the image in or out in 10% steps.

Adding the Shift key causes the zoom increment to increase to full steps (e.g., 100%, 200%, etc.)