8.4. One-Click Fixups: The Enhance Button
The Enhance button provides a simple way to improve the appearance of less-than -perfect digital photos. You click one button to make colors brighter, skin tones warmer, and details sharper. (If you've used Photoshop, the Enhance button is a lot like the Auto Levels command.)
But if you want to know exactly what the Enhance button does, well, good luck. Apple guards that information as though it's a top-secret meatloaf recipe. iPhoto's online help makes only a nebulous statement about it "improving colors," but provides no explanation as to how they're improved.
What's clear is that the Enhance button analyzes the relative brightness of all the pixels in your photo and attempts to "balance" the image by dialing the brightness or contrast up or down and intensifying dull or grayish-looking color. In addition to this overall adjustment of brightness, contrast, and color , the program makes a particular effort to identify and bring out the subject of the photo. Usually, this approach at least makes pictures look somewhat richer and more vivid , as shown in Figure 8-2.
8.4.1. Using the Enhance Button
If you're editing a photo in iPhoto's main window, you'll find the Enhance button on the lower pane of the window, along with iPhoto's other editing tools. To enhance a photo, just click the Enhance button. That's itthere's nothing to select first, and no controls to adjust.
Tip: You can also Control-click a photo to choose Enhance from the shortcut menu.
As you use the Enhance button, remember that iPhoto's image-correcting algorithms are simply best guesses at what your photo is supposed to look like. It has no way of knowing whether you've shot an overexposed , washed-out picture of a vividly colored sailboat, or a perfectly exposed picture of a pale-colored sailboat on an overcast day.
Consequently, you may find that Enhance has no real effect on some photos, and only minimally improves others. Remember, too, that you can't enhance just one part of a photo. When you click the Enhance button, iPhoto runs its enhancement routine on the entire picture. If you want to selectively adjust specific portions of a picture, you need a true photo-editing program like GraphicConverter or Photoshop Elements.
Tip: If using the Enhance command does improve your photo, but just not enough, you can click it repeatedly to amplify its effectas many times as you want, really. It's just that applying Enhance more than three times or so risks turning your photo into digital mush.If you go too far, remember that you can press -Z (or choose Edit Undo) to backtrack. In fact, you can take back as many steps as you like, all the way back to the original photo.