This picture needed more contrast in the background, but not on the rocks. Masks made it happen.

If you have Adobe Photoshop and don’t know how to use Masks, you’re wasting the program’s power. Masks, when used in combination with Layers or Adjustment Layers, are the single best way to adjust specific zones of your image independently.

All you have to do is make a change to your image on one layer, add a mask, then use the mask to hide or reveal the change you made—only in the areas where you want to see it. This works when you want to add, say, contrast, saturation, or sharpness to a specific zone. Masks are also useful in compositing.

Here is a tutorial that focuses on the basics of the ways Masks function. Follow these steps, and you’ll be able to translate your knowledge to making targeted adjustments to your pictures. These instructions are for Photoshop CS5, but are simple enough to be used in any modern version of Photoshop, as well as Photoshop Elements 9. (Previous versions of Elements have Mask functionality only with Adjustment Layers.)

Tips and Shortcuts:
To hide your mask, hold down the Shift key on your keyboard and click on the layer’s mask icon (you’ll see a red X when it’s hidden). Shift + click again to get rid of the X. To see the mask itself, hold down the Alt key (Option on a Mac), and click on the mask icon. This can be useful to check if you’ve missed a spot. Click on the main layer thumbnail or another layer to return your view to normal.