Apogee Help : Working with Apogee Impose : Page Previews
Page Previews
If pages have been assigned to the Run List, you can view thumbnail previews in Product View as well as Press Sheet View. The job with placed pages does not have to be submitted for you to see the thumbnails.
NOTE: In the Normalizer, select the Create Low Resolution Previews option to obtain page previews with a higher resolution in the Press Sheet View.
To see page previews in Product View 
*Choose View > Show Page Preview to preview thumbnails of the pages already placed in the Run List.
To see page previews in Press Sheet View 
*Choose View > Show Page Preview to preview thumbnails of the pages already placed in the Run List
OR
Select Page Previews in the View Options palette.
NOTE: Use the shortcut CTRL+SHIFT+T to switch thumbnails on and off while working in Product or Press Sheet View.
doc. version 13.1.1
Low Resolution Previews