Apple Aperture 2 - Manual (Page 494)

494 Part IV Distribution and Backup
To specify the dpi setting for exported images in an export preset:
1 Select the image or images you want to export.
2 Choose File > Export > Versions (or press Command-Shift-E).
3 Navigate to the location where you want the exported images placed.
4 Choose Edit from the Export Preset pop-up menu.
The Export Presets dialog appears.
5 Select an export preset, then enter the dpi setting you want.
6 Specify additional settings as necessary, then click OK.
7 Choose a name format from the Name Format pop-up menu, then click Export Versions.
Enter a dpi setting for
exported images here.