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Hack 63 Secrets of Sharpening

Every digital photographer knows that some
pictures need a little sharpening, but few understand the best way to
do it. Here's how.

I could tell you about the years of trial and error in which
I've experimented with different sharpening settings, the countless
articles I've read on the subject, or the debates in
which I've engaged with other knowledgeable
photographers. Or, I could just show you what I've
learned through all those experiences. I'll give you
the shortcut.

Regardless of whether you're using Photoshop 7, CS,
or Elements, this hack works the same. The only sharpening tool I
recommend is Unsharp Mask, which works its magic on the edges of the
pixels by increasing their contrast. The more contrast, the sharper
the image appears.

You'll need to use this tool after
scanning and when you sample down a
picture [Hack #64] .
Unsharp Mask can also help when your picture appears a little soft
because of less-than-perfect photo technique. But it can improve
things only so much, so always try to record the sharpest image you
can.

Apply Unsharp Mask as the last step in your image-adjustment process. If you apply it early, other adjustments could degrade its effect and you'll have to do it again.

First, open your image and choose Unsharp Mask from the Sharpen menu
(FilterSharpenUnsharp Mask). Make sure the
Preview box is checked. You'll see a close-up sample
of your picture in the preview box, as shown in Figure 6-3. If you want to see a close-up of a different
area of the picture, just click the mouse button and move the mouse
around inside the preview pane.

Figure 6-3. Unsharp Mask in Photoshop Elements

Enter these settings in the three fields of the dialog box:

Amount: 12%

Earlier, I mentioned that Unsharp Mask works its magic by increasing
the contrast on the edges of the pixels. The Amount setting specifies
the amount of contrast. Keep this setting low, around 12%. If the
effect isn't strong enough, repeat the process.
It's better to apply the filter three times at 12%
than one time at 36%.

Radius: 1.0 pixels

As you apply these changes to the pixels in your image, they also
affect the pixels adjacent to them. This is important to keep the
picture looking natural and not too digital. The larger the number
you set in the Radius field, the wider the band of adjustment that
affects other pixels will be. You want to keep this setting at 1 or
2. Beyond that, your picture will lose too much detail.

Threshold: 4 levels

This setting looks at the amount of contrast between neighboring
pixels and applies sharpening to them. If the setting is set to 0
(the lowest threshold), all the pixels in the picture get sharpened.
If the setting is high20, for exampleonly areas of the
image with substantial contrast between pixels get sharpened. A
setting of 4 is a good starting point. If you leave the setting at 0,
the default in Photoshop, every pixel edge will be sharpened. This
can unduly increase image noise and make smooth areas, such as skin
tones, look a little blotchy. The general range for this setting is
between 2 and 20.

Click OK and inspect your picture. If you feel it needs a bit more
sharpening, repeat the process or use the keystroke combination
Ctrl-F, which repeats the last filter you applied. These settings are
designed to maintain as much quality as possible while still
producing the desired sharpening effect. You can apply them two,
three, or even four times to a picture, as necessary.