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

How the Saturation Adjustment Works

iPhoto inherits several professional-quality adjustments from its powerhouse sibling, Aperture: shadow and highlight recovery, and the Definition adjustment.

The Saturation adjustment also borrows from Aperture. When the Avoid saturating skin tones option is active in the Adjust pane, iPhoto is actually using an Aperture adjustment called Vibrancy. No, the slider’s name doesn’t change to Vibrancy, but under the hood, iPhoto is applying the same basic approach to adjusting the photo’s colors—a selective saturation adjustment that preserves the color of skin tones.

This won’t affect how you use the adjustment, but it’s a fun piece of iPhoto-geek trivia: when the box is checked, the adjustment is Vibrancy. When ...