Okay, you’ve already learned that sharpening totally rocks, but the more you use it, the more discerning you’ll become about it (you basically become a sharpening snob), and at some point, you’ll apply some heavy sharpening to an image and notice little color halos. You’ll grow to hate these halos, and you’ll go out of your way to avoid them. In fact, you’ll go so far as to use this next sharpening technique, which is fairly popular with pros shooting digital (at least with the sharpening-snob crowd).
Open a photo that needs some moderate to serious sharpening.
Duplicate the Background layer ...