In Photoshop, when you think edges, you should think filters. Unsharp Mask enhances the contrast of pixels along edges, thus creating the appearance of sharper focus. Unsharp Mask Quite simply, Unsharp Mask is the only sharpening command you'll ever need. The first two are far and away the most important. Vary the Amount value from 1 to 500 percent.
Larger values result in more sharpening.
The Radius value controls the thickness of the sharpened edges. If you want thin, crisp edges, use a low value such as 0.5. If you want thick edges, try a value of 1.0 or higher. Values of 3.0 or higher are generally reserved for special effects. Higher resolutions require higher Radius values.