Apple has updated Aperture 2 with latest version 2.1.2, which is availble for download here. The Aperture 2.1.2 update improves the printing quality of books, cards and calendars ordered through the Aperture printing service. The update is recommended for all customers using Aperture 2.
If you’re unable to upgrade to Aperture 2, updates for earlier versions of Aperture are also available on this page. (login required)