Image Preview is available for images that are larger that the handheld device's screen (larger than 160 by 160 pixels). The preview shows the whole image on the screen in a smaller format. Tap on the preview image to enlarge it, centered on the point where you tapped.
Tap the silk-screened 'menu' button to display the option bar. The option bar has pushbuttons which perform the same actions as the option bar on the Image List View, with the addition of a 'Return to List View' pushbutton.
Another way to return to the Image List View is to tap the silk-screened 'menu' button twice.