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S H A R P E N I N G   Y O U R   I M A G E:

The purpose of image sharpening is to make the photograph seem sharper by accentuating the boundaries between areas of different tone. It won't bring a badly out-of-focus image into sharp focus, but it will make a good image seem much bettter.

 

Sharpening is a process that is applied to digital images as a  last stage in image processing after you have made all your colour adjustments and size ajustments.  Usually you save your file before applying sharpening.

 

The most commonly applied method of sharpening in Photoshop is to use "UNSHARP MASK". Go to the filters menu, and then choose "sharpen", followed by "unsharp mask". The following settings make good starting points for experimentation:

 
A M O U N T
R A D I U S
T H R E S H O L D
ALL PURPOSE
85
1.0
4
MODERATE*
225
0.5
0
PORTRAITS
75
2.0
3
SOFT SUBJECTS
150
1.0
10
WEB IMAGES
400
0.3
0
MAXIMUM*
65
4
3

* Use this setting to sharpen images with lots of detail with sharp edges.
* Use this setting only to help rectify mildly out-of-focus images
 
E D G E - E F F E C T S:
When sharpening an image it is important to check for unwanted edge-effects before printing a photograph. Zoom in to look at your photograph in detail and look for a pale halo around fine detail. This can mean that you have over-sharpened your image. Go back and try a less intensive level of sharpening. (There are one or two other ways of reducing these edge effects. These are generally complex, but one is given as a recipe at the bottom of this page).
 
It is always best to turn off your in-camera sharpening, and then do all your sharpening later on when you process your image. This way you are not sharpening your photograph twice.

 
 
A P P E N D I X :
 
R E D U C I N G   E D G E - E F F E C T S   U S I N G  L U M I N A N C E:
 
Try the following Photoshop workflow technique to reduce possible edge-effects caused by sharpening:
 
1.  OPEN YOUR IMAGE FILE
    (File > Open > Filename)
 
2.  MAKE A DUPLICATE COPY OF THE IMAGE AS A NEW LAYER.
    (Layer > Duplicate Layer)
 
3.  APPLY SHARPENING USING "UNSHARP MASK". (SEE TABLE ABOVE FOR GUIDANCE ON SETTINGS).
    (Filter > Sharpen > Unsharp Mask)
 
4.  CHANGE BLENDING MODE OF TOP LAYER TO "LUMINANCE"
    (In the  Layers palette use the drop-down menu to choose luminance"
 
5.  ADJUST THE OPACITY OF THE TOP LAYER TO GET THE DESIRED EFFECT.
    (In the layers palette click on opacity and adjust slider that appears).
 
6.  FLATTEN YOUR FINAL IMAGE FILE
   (Layer > Flatten Image)
 
7. PRINT YOUR FILE
 
 

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Added 9 February 2008