Aperture provides a powerful feature for managing these tough choices—it's called a "stack." A stack groups several images of which you only intend to use one, known as the "pick." You can create stacks automatically at time of import or any time after; you can manually create stacks, or mix both methods.
When you place a stack in a book or web journal, Aperture automatically uses the pick. If you try to drag a non-pick image onto a web journal or book page, Aperture will remind you to use a pick.
Changed your mind? You can change your pick almost as quickly. A change to your pick will apply anywhere that the stack appears, so you don't have to bother with updating each location. The exception is that if you want to keep your current pick for general use but have a non-pick in one particular location, you can make it an "album pick."
If you decide that you want to use two images from a stack independently of each other, you can extract one of them from the stack, split the stack, or unstack the images—but remember that will affect the stack everywhere that it appears. If you want to use an image outside the stack while keeping the stack intact, just hold the Option key and drag the image to a location in the browser outside the stack, thus making a copy.
There's three places to find stack commands: Control-click a stacked image to access the shortcut menu, open the Stack menu in the menu bar, or use the keyboard shortcuts from the table below.
Keyboard shortcuts for working with stacks
|Select previous stack||Option–Page Up|
|Select next stack||Option–Page Down|
|Open all stacks||Option-apostrophe (‘)|
|Close all stacks||Option-semicolon (;)|
|Set stack pick||Command-backslash (\)|
|Promote stack item||Command–left bracket ([)|
|Demote stack item||Command–right bracket (])|