To access the zoom mode of the program click on the zoom tool 
located in the
tools panel of the main window
or select
from the main menu. In this mode you may click anywhere on the image to zoom in (magnify) or click while holding the
Alt key to zoom out (reduce). You may also click and drag to fit a specific area to the viewport (See image below).
TIP: Pressing the Z key will switch to this mode as well.
Selecting in the menu automatically adjusts the zoom factor for the current view so that the image data fits the window. Selecting in the menu sets the magnification factor to 100 percent (no magnification).
TIP: These zooming operations are also available as a context menu by right-clicking on the image when in zoom mode. See image below.
To keep the image centered within the display window, select the menu item . Select this item again to turn this feature off. Note that the image is only centered in the dimensions that fit completely within the display at the current zoom factor.
TIP: If your mouse has a scroll wheel it may be used in any of the edit modes to quickly zoom in and out of the display.