Sharpening a Photo with the Unsharp Mask
This is the simplest technique that can be used to sharpen an image.
Proceed as follows:
In the Layer palette select the layer to be sharpened (most probably the background layer).
Open the Unsharp Mask dialog window (Filter > Sharpen > Unsharp Mask).
Play with the Amount, Radius, and Threshold settings until you’re satisfied with the result, then click OK.
The following two pictures show the effect of an unsharp mask with amount set to 125%, radius to 1.5 pixels, and threshold to 1:
 Original picture |
 Unsharp mask |
Note that once the unsharp mask has been applied onto a layer, it’s effect cannot be reverted after the file has been closed. The unsharp mask also increases noise in the image (play with the Threshold setting to attenuate this).
Some references:
- Behind the Unsharp Mask: The Secret World of Sharpening (Earthbound Light)
- Understanding the Digital Unsharp Mask (Luminous Landscape)
- Sharpening: Unsharp Mask (Cambridge in Colour)
Older: Convert a Photo to Black and White with a Gradient Map Layer