Apple Aperture Getting Started - Manual (Page 90)

90 Chapter 7 Displaying Images in the Viewer
To display the currently selected image in the secondary Viewer,
do one of the following:
m Choose View > Secondary Viewer > Alternate (or press Option-A).
m Choose Alternate from the Viewer Mode pop-up menu in the control bar.
To display the same images in both the primary and secondary Viewers,
do one of the following:
m Choose View > Secondary Viewer > Mirror (or press Option-M).
m Choose Mirror from the Viewer Mode pop-up menu in the control bar.
To display a selection of images across both the primary and secondary Viewers,
do one of the following:
m Choose View > Secondary Viewer > Span (or press Option-S).
m Choose Span from the Viewer Mode pop-up menu in the control bar.
To turn off the display of images in the secondary Viewer,
do one of the following:
m Choose View > Secondary Viewer > Blank (or press Option-B).
m Choose Blank from the Viewer Mode pop-up menu in the control bar.
To turn off the secondary Viewer function, do one of the following:
m Choose View > Secondary Viewer > Desktop (or press Option-X).
m Choose Desktop from the Viewer Mode pop-up menu in the control bar.
Choose Alternate from
the Viewer Mode pop-up
menu to display the
selected image in the
secondary Viewer.