By Steve T. (Rohirrim) Selective Sharpening Selective sharpening is a method of only sharpening a portion of an image. The main advantage of Selective Sharpening is to minimize sharpening artifacts that occur when an image is sharpened. These artifacts are often amplified in images with lots of blue sky or with nice blurry backgrounds. For this reason it fits with bird photography very well. This technique can also be used for portraits when you only want to sharpen the eyes for example.
Sharpen your image There are many ways to sharpen an image. There are a couple of good tutorials on dgrin Basic Sharpening and USM Theory as well as Smart Sharpen etc. Try several methods and choose the one that works for you. Here I've used just basic unsharp mask.
Layer Mask This shows a black layer mask on the sharpened layer. Black areas of a mask are "masked" or invisible. White areas of a mask are "unmasked" or visible. Think of the black areas as covered up with masking tape and the white areas are where you peeled the tape off. This will hopefully make more sense once you finish the tutorial.
Paint in the areas to be unmasked Make sure your foreground color is white. Paint in the areas of the image to "unmask". You will see the areas that you are painting in white show up on the layer palette. If you make a mistake and paint in too much, just make your foreground color black and re-paint the areas you need to.