iPhoto ’11: The Macintosh iLife Guide to using iPhoto with OS X Lion and iCloud

Entering Custom Crop Proportions

With the Constrain pop-up menu in edit view, you can tell iPhoto to restrict cropping rectangles to standard proportions (page 53). If you want non-standard proportions, choose Custom from the Constrain pop-up menu and enter the proportions in the boxes that appear. Note that you can’t enter fractional values: 8.5, for example, is rounded up to 9.