Sharpening
Obviously, you failed to detect the subtle diamond
pattern in my tie.
—Niles Crane, on the TV show Frasier
Sharpening
Almost all digital images start life looking slightly soft.
Too often, they’re left that way when sent to the Web or to
print. This chapter is about those very subtle details that
can make the difference between a so-so image and one
that pops off the page.
It’s just a fact of life that all of our capture devices (digital
cameras, scanners, and so on) can’t deliver as much detail
as the original image contained. (High-end drum scans
are the one exception because they get sharpened dur-
ing the scanning process.) Only images that are created
from scratch in Photoshop or another program such as a
3D rendering application will be 100% sharp. Even those
images can become soft if you attempt to make the image
larger or smaller in Photoshop (known as interpolating the
image). Finally, when you output the image to an inkjet
printer, printing press, or other output device, you’ll lose
212
Figure 6.1 An image out of the cam-
era is okay, but could benefit from
Photoshop’s sharpening tools. (©2008
Dan Ablan.)
Figure 6.2 The image from Figure
6.1—what a difference sharpening
makes!
additional detail because most output devices simply are
incapable of reproducing the amount of detail you see
onscreen. By exaggerating the differences between areas
(sharpening), we can attempt to compensate for all the
factors that can make an image look soft.
After you learn how to sharpen images properly, they’ll
look much crisper when you print them, and will be an
obvious improvement over unsharpened scans (Figures 6.1
and 6.2). But no matter how much sharpening you apply
to an image, it won’t compensate for an out-of-focus origi-
nal, so try to stick with images that aren’t overly blurry.
II: Production Essentials
Removing Film Grain and Scanner/Camera Noise
Sharpening an image will exaggerate almost all the detail
in the image, so any film grain will also be exaggerated
(Figures 6.3 and 6.4). That’s fine if you want an image
with pronounced grain, but if you prefer a smoother look,
check out the techniques in this section for removing grain
from images. As we get into this topic, much of the time
we’ll refer to film grain as noise.
Figure 6.3 An old black-and-white
image scanned from a 35 mm nega-
tive can have some film grain.
(©2008 Dan Ablan.)
Figure 6.4 When sharpened, the
noise in the image from Figure 6.3 is
exaggerated.
213
Chapter 6 Sharpening
Five main filters are used to remove noise from images:
Gaussian Blur, Despeckle, Median, Dust & Scratches, and
Reduce Noise. Let’s look at these filters one at a time, start-
ing with the least sophisticated and moving to the most
advanced. As each filter is described, we’ll show the results
on two images: a simple image that contains black dots of
different sizes representing noise (as in Figure 6.5) and
a normal image (as in Figure 6.6) to show how much the
filter trashes the real detail in the image. You’ll be able to
see how effective each filter is at removing noise, while at
the same time learning how much image detail is lost in
the process.
Figure 6.5 This image contains black
dots that vary from one pixel to over
25 pixels wide.
Figure 6.6 A normal image with some noise. (©2008 Dan Ablan.)
Gaussian Blur Filter
The Gaussian Blur filter (Filter > Blur > Gaussian Blur)
does the opposite of what we’re trying to accomplish
when sharpening an image—it makes the transitions in
the image less distinct, rendering the image less sharp
(Figures 6.7 and 6.8). This is a common method used to
remove noise; however, just because it’s common doesn’t
mean that you should always use it. Much more sophisti-
cated methods are available that won’t trash the general
detail in the image.
214
II: Production Essentials
Figure 6.8 A setting of 5.0 pixels was
necessary to blend the smallest dots
from the example in Figure 6.5 into
the surrounding image.
Figure 6.7 After blurring the image, it looks nowhere near as sharp as the
original in Figure 6.6.
Despeckle Filter
The next few filters we’ll explore are found in the Noise
menu (Filter > Noise). The first choice in that menu is
Add Noise, which is designed for adding specks to an
image; the rest of the filters in the menu get rid of noise.
The Despeckle filter blends the tiniest specks into the
surrounding image, while leaving the major detail in the
image untouched (Figures 6.9 and 6.10). The only prob-
lem with this filter is that it isn’t always strong enough to
remove noise completely from the image. If an image has
minimal noise, give this filter a try; but when the noise
in the image is considerable, try the other options in the
Noise menu.
215
Chapter 6 Sharpening
Figure 6.9 After applying the
Despeckle filter, the single-pixel speck
from the example in Figure 6.5 has
changed to a light gray speck (barely
visible here).
Figure 6.10 After applying the Despeckle filter to the image from Figure 6.6, the
film grain has started to blend into the surrounding image. It’s a subtle effect,
difficult to see in print, so try it for yourself.
Median Filter
The Median filter (Filter > Noise > Median) uses an inter-
esting approach to rid an image of unwanted noise—it
rounds the corners of things, which causes tiny specks to
implode. As you increase the Amount setting, the filter
rounds the corners to a larger degree, which makes larger
specks in the image blend into the surrounding image
(Figures 6.11 and 6.12). What’s really nice about this filter
is that it doesn’t make anything look blurry. You don’t usu-
ally need to use settings above 2 when applying this filter.
Figure 6.11 Using the Median filter
with a Radius of 1 (its lowest setting)
effectively removed the small specks
from the example in Figure 6.5.
Figure 6.12 Applying the Median filter to the image from Figure 6.6 causes it to
lose some detail, but it doesn’t get blurry.
216
II: Production Essentials
Dust & Scratches Filter
The Dust & Scratches filter (Filter > Noise > Dust &
Scratches) uses the same technology as the Median filter,
but it adds a Threshold setting to determine which shades
in the image should be affected by the filter. A setting
of zero allows the filter to apply to the entire image, and
will therefore work exactly like the Median filter. Raising
the Threshold setting limits the changes to areas that are
similar in brightness. The general idea here is to start with
a Threshold of zero so you work on the whole image, and
then adjust the Radius setting until the noise in the image
is gone. Then, to make sure that you lose the absolute min-
imal amount of true detail, change the Threshold setting
to 255 and use the down-arrow key to change that setting
slowly until you find the highest number that will rid the
image of unwanted noise (Figures 6.13 and 6.14).
Figure 6.14 Using the Dust &
Scratches filter with a Radius of 2 and
a Threshold of 8 on the example from
Figure 6.5 produced the same result
on our specks as the Median filter
(Figure 6.11).
Figure 6.13 Dust & Scratches results on the image from Figure 6.6.
Reduce Noise Filter
The Reduce Noise filter (Filter > Noise > Reduce Noise) is
the most sophisticated method for reducing noise. It incor-
porates many of the tricks that we used to do piecemeal
by using blending modes or applying filters to individual
channels. It often produces a result that looks smooth
while retaining much of the detail from the original image
217
Chapter 6 Sharpening
(Figures 6.15 and 6.16). When applying the Reduce Noise
filter, start by moving all the sliders to the far left so they
have no effect on the image. Then adjust them gradually.
Figure 6.15 Using the Reduce Noise
filter with a Strength of 10 and a
Preserve Details setting of 1 produced
minimal distortion in the largest
specks from the example in Figure 6.5,
while making the smaller specks fade
into their surroundings.
Figure 6.16 The Reduce Noise filter produced a somewhat smoother result on
the image from Figure 6.6 than the Dust & Scratches filter did in Figure 6.13,
while retaining more highlight detail in the subject.
If you notice multicolored noise in the image (specks of
yellow, blue, red, etc.), adjust the Reduce Color Noise
slider until those colors blend into their surroundings
(Figures 6.17 and 6.18). If the noise is primarily a single
color, consider applying the features found in Advanced
mode (which we’ll talk about next) before continuing with
the techniques mentioned here.
218
Figure 6.17 This original image contains specks of various
colors. (©2008 Dan Ablan.)
Figure 6.18 The result of adjusting the Reduce Color Noise
slider for the image from Figure 6.17.
II: Production Essentials
After tackling any color noise problems, it’s time to rid the
image of luminance noise (specks that vary in brightness
instead of color). Adjust the Strength slider until you’ve
removed as much of the remaining noise as possible. Move
the Preserve Details slider all the way to the right and
then lower it until you find the highest setting that gives a
good balance between noise reduction and image detail
(Figure 6.19).
Figure 6.19 The Reduce Noise filter
helps bring down noise within a
scanned image.
Images saved in the JPEG file format will exhibit artifacts
that make the image look as if it has been divided into
squares of 8 × 8 pixels. You can attempt to blend those
squares into the surrounding image by turning on the
Remove JPEG Artifact check box. Just remember to inspect
the image to make sure that this option doesn’t destroy too
much important detail in the image.
Advanced Mode
If the image has very fine detail or considerable noise,
you’ll need to take additional steps to ensure that you
don’t trash too much detail in the image when you’re
attempting to remove noise. Color images are made out
of three (RGB) or four (CMYK) color components, which
are known as color channels. It’s rather common to find
more noise in one of those channels than the others
219
Chapter 6 Sharpening
(Figures 6.20 to 6.22). When that’s the case, try applying
the noise removal filters to the individual channels before
attempting to reduce noise from the image as a whole;
otherwise, you might trash the detail in most of the chan-
nels just to rid one pesky channel of noise (usually the
blue or yellow channel). The next time you need to be
heavy-handed with the Strength slider in the Reduce Noise
dialog, try setting it to zero, switch to Advanced mode
at the top of the dialog, and then click the Per Channel
tab (Figure 6.23). After you’ve done that, you can cycle
through the RGB or CMYK channels to see whether the
noise shows up more in one channel than another, and
adjust each channel accordingly. When you’ve done all
you can to the individual channels, click the Overall tab
and adjust the image further to bring back some detail
(Figure 6.24).
Figure 6.20 The red channel. (©2008
Dan Ablan.)
Figure 6.21 The blue channel. Figure 6.22 The green channel.
220
Figure 6.23 In Advanced mode, you can reduce noise in
individual channels.
Figure 6.24 After reducing noise independently in chan-
nels, you can go back and adjust the overall image quality.
II: Production Essentials
Reclaiming Detail with the History Brush
Applying one of the noise reduction filters may cause an
image to lose important detail such as eyes or freckles.
If you use the History Brush immediately after applying
the noise reduction filter, you can paint back the desired
detail, effectively removing the effect of the filter from the
areas across which you’re painting. If the History Brush
presents a “no” symbol (circle with a diagonal line across
it), you’ve either changed the dimensions of the image or
changed the color mode of the image since you opened it.
When that’s the case, choose Window > History and click
to the left of the history state that’s directly above the list-
ing for the noise reduction filter you just applied (Figure
6.25). After you’ve done that, the History Brush should
work on the image. Paint across the areas that have lost
important detail, and the details should come back.
Now that you’ve seen how to rid images of unwanted noise
and film grain, let’s examine how sharpening can exagger-
ate detail, and then we’ll explore the exact steps needed to
sharpen any image.
How Sharpening Works
To sharpen an image, choose Filter > Sharpen. Photoshop
presents a submenu of choices (Figure 6.26) on which the
top three options might sound friendly (Sharpen, Sharpen
Edges, and Sharpen More), but you might want to ignore
these techniques; they’re simply presets that enter differ-
ent numbers into the bottom choice, Unsharp Mask. The
bottom two filters in the list are the only ones that allow
you to control exactly how much the image will be sharp-
ened. We’ll start by exploring the Unsharp Mask filter and
then refine your knowledge by exploring Photoshop’s
Smart Sharpen filter.
Unsharp Mask has this confusing name because way back
before people used desktop computers, they sharpened
images in a photographic darkroom. They would have
Figure 6.25 Click just to the left of the
history state that’s directly above the
one that lists a noise reduction filter.
You can also use the History Brush
with its blending mode set to
Lighten or Darken to rid the image
of sharpening-related halos. Use
Darken mode to remove the bright
halos and Lighten mode to remove
the dark halos.
Figure 6.26 Photoshop’s sharpening
options.
to go through a process that involved a blurry (unsharp)
version of the image. This process would take well over an
221
Chapter 6 Sharpening
hour (don’t worry—in Photoshop it takes only seconds)
and wouldn’t be much fun. The process they’d go through
in the darkroom was known as making an unsharp mask, so
Adobe just borrowed that term.
The Unsharp Mask filter increases the contrast where two
colors (or shades of gray) touch in the image, making their
edges more prominent and therefore easier to see. To view
the effect of the Unsharp Mask filter (Figure 6.27), we’ll
demonstrate using two documents: Figure 6.28 contains
only three shades of gray (20%, 30%, and 50%), and
Figure 6.29 is a normal photographic image.
Figure 6.27 The Unsharp Mask dialog.
Figure 6.28 This simple document
contains only three shades of gray.
The Unsharp Mask dialog contains three sliders:
Amount: Determines how much contrast will be added
to the edges of objects—and, therefore, how obvious
the sharpening will be (Figure 6.30).
Radius: Determines how much space will be used for
the contrast boost that the Amount setting creates. No
matter which settings you use, sharpening will produce
a bright halo on one side of the edge of an object and a
dark halo on the opposite side of that same edge. If you
sharpen too much, you’ll add a very noticeable glow
around the edges of objects instead of a barely notice-
able halo (Figure 6.31).
Threshold: Determines how different two touch-
ing colors have to be for sharpening to kick in. With
Threshold set at 0, everything will be sharpened. As
you increase this setting, only the areas that are drasti-
cally different will be sharpened (Figure 6.32). If the
setting is too low, unwanted artifacts like noise and
film grain will be exaggerated and relatively smooth
areas might start to show texture. If the setting is too
high, the sharpening will apply to very few areas in the
image, which will look too obvious because those areas
won’t fit in with their surroundings (which didn’t get
sharpened).
Figure 6.29 This will be our
photographic reference image.
(©2008 Dan Ablan.)
222
II: Production Essentials
Figure 6.30 The effect of the Amount setting—left to right, settings of 100, 200, and 500. (©2008 Dan Ablan.)
Figure 6.31 The effect of the Radius setting—left to right, settings of 1, 2, and 5.
223
Chapter 6 Sharpening
Figure 6.32 The effect of the Threshold setting—left to right, settings of 0, 10, and 50.
Now that we’ve explored all the options that are available
with the Unsharp Mask filter, let’s get down to business
and find out how to apply them to an image. But before
you start applying the Unsharp Mask filter, double-click the
Zoom tool in the toolbar to view the image at 100% view;
otherwise, you won’t be able to see the full effect of the
sharpening you apply to the image.
Sharpening an Image
Load any image you might have on your drive, from a scan
to a digital camera image. Then, to sharpen the image,
choose Filter > Sharpen > Unsharp Mask and type the
following generic settings: Amount = 500, Radius = 1, and
Threshold = 0, just to make sure that you can easily see the
effect of sharpening the image (Figure 6.33). Now adjust
the Threshold setting. With Threshold set to 0, everything
in the image will be sharpened. That can cause areas that
used to have fine detail (such as a brick wall) or areas that
Figure 6.33 Start with the generic settings of
500, 1, and 0. (©2008 Dan Ablan.)
224
used to look relatively smooth (such as a skin tone or a
shadow) to have overly exaggerated detail. Those bricks
II: Production Essentials
look noisy, and a Threshold setting of 0 will add years to
anyone’s face because you’ve exaggerated every imperfec-
tion. To avoid that problem, slowly increase the Threshold
setting until those areas smooth out (Figure 6.34). You’ll
usually end up using settings in the single digits. From
there, bringing the Amount value down can help to make
the sharpening cleaner.
Next, experiment with the Radius setting, trying to find
the highest setting that makes the image look like it’s been
sharpened—but without making it look like everything is
glowing—usually in the range of .5 to 2 (Figures 6.35 and
6.36). Images with very fine detail look best with lower
Radius settings, whereas images that contain little detail
or that will be printed in large sizes and viewed from a
Figure 6.34 Adjust the Threshold setting until areas
that should be smooth look smooth.
distance look best with higher Radius settings.
Figure 6.35 This Radius setting is too high. Figure 6.36 Try to find the highest Radius setting
that doesn’t make objects look like they’re glowing.
Finally, adjust the Amount setting until the image looks
naturally sharp instead of artificial, usually in the range
of 15 to 250, depending on the Radius setting you used
(Figure 6.37). Let your eyes be your guide. There are two
common indicators that the Amount setting is too high:
Obvious bright halos appear around the edge of
objects. (There will always be halos; you just want to
make sure that they aren’t very noticeable.)
Very fine detail (like hair, or texture in bricks) will become
overly contrasty—almost pure black and pure white.
225
Chapter 6 Sharpening
Figure 6.37 Adjust the Amount set-
ting until the image looks realistically
sharp.
The procedure we’ve just discussed is the usual approach
to sharpening most images, but sometimes you’ll need to
go a different route. The Radius setting can have a radi-
cal effect on sharpening. You’ll need to achieve a bal-
ance between Amount and Radius. High Amount settings
(about 90–250) will require low Radius settings (.5–1.5),
and low Amount settings (10–30) will require higher
Radius settings (5–20). High Amount settings work for
most images, and that’s why we took the initial approach
just mentioned.
If you have a grainy image and you want to maintain but
not exaggerate the grain (Figure 6.38), you’ll need to take
a slightly different approach. A grainy image will start to
look unusual when you get an Amount setting anywhere
near 100–150 (Figure 6.39); you might even need to bring
the Amount setting down to near 20 before the grain stops
being exaggerated too much. At that point, you’ll barely
be able to tell that the image has been sharpened (Figure
6.40); to compensate, you’ll need to get the Radius setting
up until the image starts to look sharp (Figure 6.41). On
most images, you’ll be able to use much higher Amount
settings without causing grain problems. In that case, you
might end up with an Amount setting around 120, and
then you’ll need to experiment with the Radius setting to
see what looks best (probably between .5 and 1.5).
226
II: Production Essentials
Figure 6.38 An old grainy image. (©2008
Dan Ablan.)
Figure 6.40 With the Amount setting at 20,
the grain is less, but the image doesn’t look
sharp.
Figure 6.39 With the Amount setting at 150,
the grain is becoming too obvious. (Look
very closely to see the difference between
this figure and Figure 6.38.)
Figure 6.41 With the Amount setting at 20
or so and the Radius up to 1.5, the image
becomes sharp.
227
Chapter 6 Sharpening
Using Smart Sharpen
The Smart Sharpen filter (Figure 6.42) expands on the
concepts of the Unsharp Mask filter to deliver a more
sophisticated method for sharpening images. However,
there are many instances where you might prefer the
Unsharp Mask filter, for reasons explained in a moment.
Figure 6.42 The Smart Sharpen
dialog, with the Remove option set to
Gaussian Blur. (©2008 Dan Ablan.)
The Amount and Radius settings in the Smart Sharpen
filter work just like the ones in the Unsharp Mask filter.
In fact, the results are identical when the Remove pop-up
menu is set to Gaussian Blur (Figure 6.43). Setting the
Figure 6.43 Gaussian Blur setting.
Figure 6.44 Lens Blur setting.
Figure 6.45 Lens Blur setting with
More Accurate check box turned on.
Remove menu to Lens Blur causes the halos that come
along with sharpening to be less pronounced, which allows
you to get away with higher Amount and Radius settings
before the sharpening halos become overly obvious
(Figure 6.44). You can use this setting whenever quality
is more important than speed (which is often the case in
normal workflow). You can also set the Remove pop-up
menu to Motion Blur and then experiment with the Angle
setting to reduce the blurring effect of lens shake. It’s not
a miracle worker, though, so it will only be effective when
the camera shake was almost unnoticeable.
Turning on the More Accurate check box causes the
image to be sharpened in two passes (just like applying the
Unsharp Mask filter twice). This can make edges much
more prominent (Figure 6.45), but you have to be very
228
II: Production Essentials
careful because it also has a tendency to over-exaggerate
grain and noise in images.
You might find that you’ll use the Unsharp Mask filter for
images that contain fine texture, such as skin or brick,
because the Smart Sharpen filter does not offer the
Threshold setting that allows you to limit the sharpening
effect to areas of more pronounced detail.
Advanced Mode
The Smart Sharpen filter also offers an Advanced mode,
which allows you to control the strength of the sharpening
that will be applied to the shadows and highlights of the
image (Figure 6.46). This feature can be useful in instances
when a considerable amount of noise is present in the dark
portion of an image. The Fade Amount setting determines
the strength of the sharpening effect; the Tonal Width set-
ting determines the brightness range that will be affected
by the sharpening, and the Radius setting determines how
the sharpening effect will blend into the surrounding
image. A good way to work is to start with Fade Amount
at 100% and Radius at 3 so that you can see the full
effect of the sharpening. Then adjust Tonal Width until
the sharpening no longer affects any overly noisy areas.
Finally, adjust the Fade Amount slider to see just how much
sharpening you can use without exaggerating the noise in
the image.
Figure 6.46 Advanced options.
229
Chapter 6 Sharpening
More Art Than Science
The process of sharpening takes a good bit of practice
before you start feeling confident. Everyone has a different
idea of how sharp an image should look, and most output
devices aren’t capable of reproducing the amount of detail
you see onscreen. Even if you sharpen the image so that it
looks great onscreen, when you print the image it might
still look rather soft. Following are some general thoughts
on how to approach sharpening for different types of
output:
Web/multimedia: When the final image will be
displayed onscreen, you can completely trust your
screen when sharpening the image. Most of the time
you’ll end up with Radius settings between .5 and 1
and Amount settings below 100%. Just be aware that
sharpening increases the file size of JPEG file format
images (Figures 6.47 to 6.49). If you’re planning to save
the image as a JPEG file, use the absolute minimum
amount of sharpening that makes the image look crisp.
Figure 6.47 The original unsharpened
image. (©2008 Dan Ablan.)
Figure 6.48 The image from Figure
6.47, sharpened with settings of
Amount 70, Tonal Width 5, and
Radius 4.
Figure 6.49 The image from Figure
6.47, sharpened with settings of
Amount 175, Tonal Width 7, and
Radius 4.
Photographic output devices: These devices include
film recorders, LightJets, and other gadgets that use
230
II: Production Essentials
photographic film or paper to reproduce an image.
They can reproduce the majority of the detail you see
onscreen. With these devices you have to be very care-
ful to make sure that the Radius setting is quite low (.25
to .7 for most images), so that the halos that come from
sharpening aren’t obvious on the end result.
Desktop printer: This includes inkjet and laser printers.
Experiment with an image that’s representative of the
type of image you use the most.
Commercial printing press: Start by sharpening images
until they look very sharp onscreen, and then analyze
the printed result when you get a job back from the
printing company. If the printed result doesn’t look
too sharp, slowly ratchet up the Amount and Radius
settings on subsequent images until the printed images
look very sharp, but still natural. Compare the printed
result to the original digital file each time, viewing the
image at 100% magnification. As you work on more
and more jobs, you’ll start to get a feeling for how
much you need to overdo the sharpening onscreen to
get a nice sharp end result. Different types of print-
ing produce differing amounts of detail. (Newspaper
images need to be sharpened much more than images
that will be printed in a glossy brochure.)
If thinking about all the different settings needed for
different output devices drives you crazy, consider adding
a commercial plug-in filter to Photoshop. Nik Software
(www.niksoftware.com) makes a set of plug-in filters known
as Sharpener Pro (Figure 6.50), which takes a lot of the
guesswork out of sharpening images. The package comes
with separate filters for different types of output (includ-
ing inkjet, color laser, offset printing, and Internet) and
compensates for different viewing distances and image
sizes, all without having to think about Amount, Radius,
and Threshold settings. The results might just be a little bit
too aggressive; if so, choose Edit > Fade immediately after
Figure 6.50 Nik Sharpener Pro takes a lot of the
guesswork out of sharpening.
applying the filter, and lower the Opacity setting a bit. It
might be a personal preference as to what you consider to
be a naturally sharp result, so the final Opacity setting will
be unique to you.
231
Chapter 6 Sharpening
Do you plan to use an image for more than one purpose?
Ideally, you should create a unique version of the image
for each use. Choose Image > Duplicate to create an
exact copy of an image. Then choose Image > Image Size
(Figure 6.51) to set the proper size and resolution for the
output device for which this particular image is destined.
Finally, sharpen the image based on your experience with
Figure 6.51 Use the Image Size dialog
to specify the size and resolution of
the image.
that particular device. As you repeat the process for other
devices, always go back to the full-sized master image
before repeating the steps.
If you simply can’t deal with one image for each device,
work with a single image and do the following: Set the
resolution to what’s needed for your most demanding
output device (the one that needs the highest-resolution
image), and sharpen for the device that looks closest to your
screen (the one that needs the least radical sharpening).
Then use that one image for all output devices. That’s
kind of like buying one shoe size for an entire basketball
team. As long as it’s large enough for the biggest person,
everyone should be able to fit in it, but it won’t be ideal
for everyone.
Tricks of the Trade
Now that we’ve talked about the general process of sharp-
ening an image, let’s start to explore some more advanced
ideas that will allow you to get more control over your
sharpening.
Sharpen Luminosity
If you look closely at a color image after it’s sharpened,
you might notice bright-colored halos around objects
that were not all that colorful in the original photo. (In
Figure 6.52, notice the green fringe around the blue
shirt.) To prevent that type of unwanted sharpening
artifact, choose Edit > Fade Unsharp Mask immediately
after sharpening an image. When the Fade dialog appears,
set the Mode pop-up menu to Luminosity and then click
OK (Figure 6.53). That will force the sharpening you just
applied to affect only the brightness of the image and will
prevent it from shifting or intensifying the colors in the
232
II: Production Essentials
image (Figure 6.54). If you read a lot of books and maga-
zine articles about Photoshop, you might discover that
many people attempt to get the same result by converting
their image to LAB mode and then sharpening the image.
The only problem with that approach is that any time you
change the mode of an image, you lose a little quality. So
try to switch modes only when you have a good reason to
do so. Fading after applying the Unsharp Mask filter gives
you the same benefits as converting to LAB mode, so try to
leave the image in its original mode when sharpening.
Figure 6.53 Use Fade directly after
using the Unsharp Mask filter to
have the sharpening affect only the
brightness in the image.
Figure 6.52 You can get colored halos around objects in an image when
sharpening.
Figure 6.54 A closeup view of the
sharpened image, now without
fringing.
Sharpen the Black Channel
If an image is destined for CMYK mode, be sure to make
an extra sharpening pass on the black channel. Just open
the Channels panel (Window > Channels), click the Black
channel, and sharpen away. Because black ink is mainly
used in the darker areas of the image, you can get away
with some rather aggressive settings. (Try these: Amount =
Remember, in order to sharpen the
black channel, the image needs to
be in CMYK mode. Choose Image >
Mode > CMYK Color.
350, Radius = 1, Threshold = 2.) Perform this sharpening
pass after you’ve already sharpened the full-color image
(Figures 6.55 to 6.57).
233
Chapter 6 Sharpening
Figure 6.55 The original image,
unsharpened. (©2008 Dan Ablan.)
Figure 6.56 Unsharp Mask filter
applied to the RGB channels.
Figure 6.57 Sharpening added to just
the black channel.
234
II: Production Essentials
Sharpen Channels Separately
Certain images don’t look good after being sharpened. For
instance, when you sharpen a face, it sometimes seems to
just fall apart, making the person look years older. Another
example would be scanned images in which color noise is
exaggerated. In those cases, consider clicking through the
channels that appear in the Channels panel and sharpen-
ing only the channels that would help the image. For light
skin, that would be the channel that’s the lightest—red
in RGB mode or cyan in CMYK mode (Figures 6.58 to
6.60). For noisy images, avoid sharpening the channel that
contains the most noise—usually blue in RGB mode or
yellow in CMYK mode. You shouldn’t use this technique
every time you want to sharpen images, but it’s something
to think about when sharpening a full-color image is doing
more harm than good.
Figure 6.58 Red channel. (©2008
Figure 6.59 Green channel. Figure 6.60 Blue channel.
Dan Ablan.)
Control Highlights and Shadows Separately
When you sharpen an image, Photoshop adds a dark halo
on one side of an edge and a bright halo on the opposite
side of the edge. When you’re working with dark back-
grounds, such as a deep blue sky, the bright halos can
be rather easy to see (Figure 6.61). Try controlling the
bright and dark halos separately so that you can minimize
the bright halo while maintaining the dark one. You can
235
Chapter 6 Sharpening
accomplish that goal by making two duplicates of the layer
you want to sharpen. Click each of the duplicate layers
and set the Blending Mode pop-up menu at the top of
the Layers panel to Lighten for one and Darken for the
other (Figure 6.62). Now you can sharpen the two layers
separately. The setting you apply to the layer that is set to
Lighten will control the bright halos; the setting on the
layer set to Darken will control the dark halo (Figure 6.63).
Figure 6.61 The bright halos in this
image are getting obvious.
Figure 6.62 Duplicate the layer twice;
set one layer to Lighten mode and the
other to Darken mode.
Figure 6.63 When you separate the
dark and bright halos, you have more
control over them.
The Next Step
If you felt like you were drowning in details in this chapter,
try a few of the techniques; then come back and read it
again, and things will start to gel. It may take you a while
to become truly comfortable with sharpening images, but
it’s well worth the time because you can transform flat and
lifeless images into ones that are lively and ready to pop
off the page. Now, here’s one more very important piece
of sharpening advice before we head to the next chapter:
Oversharpened images never look good, so if you’re ever
unsure of how much sharpening to apply, err on the side
of conservatism.