http://youtu.be/GVLu3TSKFKY
Every digital image needs sharpening. But sharpening increases the noise in the image. In this episode I show a way to sharpen only the areas that need to be sharpened — the edges between different colours or levels of brightness. All the other parts of the image are left alone and so the noise stays down.
Sharpening should always be the very last thing you do with your image.
Chris Marquard explained sharpening in Photoshop Corner No. 4 in his Tips from the Top Floor podcast.
I got the described method from the Gimp tutorial page.
Wikipedia describes the underlying process in this article about the unsharp mask. The links at the bottom of the page are very informative.
For more information and the forum visit: