Mac OS X supports the use of pictures stored in Aperture as desktop images. Open the operating system´s “System Preferences” and activate category “Desktop + Screen Saver”. Open tab “Desktop” in the left column of Aperture´s library. The file structure is similar to the media library and its categories. Use the cursor to mark the selected photograph. Mark a file or a project for display by additionally activating the “Change Picture” option. Use the dropdown box beside it to adjust the time each photograph will be in the background resp. on the desktop.