Professional Sharpening in Photoshop
Adapted from Photoshop CS4 After the Shoot (Wiley Publishing)
By Mark Fitzgerald
Version: Adobe Photoshop CS4
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I work with lots of photographers, most of them
professionals. When I first begin to work with a
new photographer, one of the first questions I
ask is how she handles sharpening in her
workflow. Thatís because sharpening is one of
the most misunderstood aspects of the postproduction
workflow. When itís done incorrectly,
it can have a detrimental effect on the final
image. If someone is making this mistake, I want
her to know before moving on to other things.
Digital photo sharpening is nothing more than
enhanced edge contrast. Photoshop tricks you
into thinking a photo looks sharper by isolating
edge detail and enhancing contrast along those
edges. One side of the edge is lightened while
the other side is darkened. The enhanced edge
contrast is referred to as haloing because of the
effect it causes along these edges.
There is no magic formula for sharpening
because the amount of sharpening for a particular
image depends on two very different things ó the content of the image and its overall
dimensions. Images with lots of edge detail, like
the bowl of silver rings shown below, can
handle more sharpening than images with fewer
hard edges, such as photos of people or a photo
of a landscape on a foggy morning. This is
because lots of sharpening adds to the feel of
the ring photo, while it would detract from the
softer feeling of the portrait or foggy landscape.
Additionally, a smaller print of this shot doesnít
need as much sharpening as a larger version
© Jordan Sleeth
Three Kinds of Sharpening
At first thought, sharpening seems like a
no-brainer. Who wouldnít want their photos to
be sharp? However, the subject is much more
complicated. The main reason is that there are
three different kinds of sharpening. Each type of
sharpening needs to be applied at the appropriate
- Capture sharpening. By their very nature,
digital image files need to have some
sharpening applied. This sharpening pass is
considered baseline sharpening. When you
shoot raw this is addressed during
conversion with Adobe Camera Raw. When
you shoot JPEG, this baseline sharpening is
applied by the camera.
Caution: Most cameras have a sharpening setting that
allows you to apply different sharpening
presets to your photos as you capture them. If
youíre shooting raw, this setting has no
permanent effect on the image. However, if you
shoot JPEG, it does have a permanent effect. I
always recommend turning off all in-camera
sharpening when shooting JPEG because itís
easy to add sharpening later, but impossible to
remove it after the original file is created.
- Creative sharpening. This type is used to
fine-tune an image creatively by selectively
modifying the sharpness of selected areas
of the image using selections or masks.
When I use the term sharpening here, I am also referring to its opposite, blurring,
which is the lack of sharpness. What this
means is that creative sharpening can be
used in the same image to sharpen
something of interest, such as someoneís
eyes, and to blur something else, like the
background around the subject. The image
does not need to be resized before this
sharpening is carried out.
The main thing to understand about
creative sharpening is that its effect is
relative to the rest of the image. The goal
isnít to make part of the image perfectly
sharp. The goal is to make part of the
image stand out from its surroundings by
sharpening it or blurring the detail
- Output sharpening. This is overall
sharpening thatís designed to prepare an
image for final output, such as printing or
onscreen viewing. This sharpening is
applied to the entire image with the intent
of getting it ready for a particular output
option. One of the things to understand here
is that size matters. A file thatís being
prepared for printing as a 5 ◊ 7 requires a
completely different sharpening scenario
than the same fi le being prepared for a 16 ◊
20. Otherwise, if the sharpening on the 5 ◊ 7
looks great, the 16 ◊ 20 will not be sharp
The reason sharpening is divided into these
three areas is because oversharpening degrades
the quality of a photo by introducing unwanted
artifacts. Oversharpening occurs when output
sharpening settings, which are stronger, are
used for capture sharpening. Later when the
image is sized and prepared for output, itís
necessary to sharpen again because the resizing
affects the first sharpening pass. When the
second sharpening pass is carried out on a
previously over-sharpened file, it can adversely
affect the quality of the image.
This also means that any creative sharpening
will be further sharpened during the output
sharpening process. Knowing this is important
because it means you need to avoid overdoing
the amount of creative sharpening.
Something you especially want to avoid when
possible is sharpening an image for output,
changing its size, and then resharpening for a
new output size. Sharpening on top of previous
sharpening adversely affects the image by
introducing unwanted artifacting ó distortions
introduced by the digital process ó causing
image details to look ďcrunchyĒ instead of
On more thing to keep in mind about sharpening
is that itís not used to fix severely blurred
images. Itís used to compensate for some of the
effects of digital capture ó whether by camera
or scanner. If your photo is a little soft in focus,
then you may be able to help it with sharpening.
But youíll never be able to make it look the way
it would have looked if it had been shot in
Photoshopís Main Sharpening Tools
No matter if youíre doing creative sharpening or
output sharpening, youíll use one of Photoshopís
two sharpening tools: the Unsharp Mask (USM)
and the Smart Sharpen filters. These filters are
very similar to one another. Iíll compare and
contrast them as you explore how theyíre used.
Using the Unsharp Mask Filter
People are often confused when it comes to
using the USM filter because the name is totally
counterintuitive. Why would someone want to
use something named unsharp to sharpen an image? The reason this sharpening filter has
such an odd name is that it refers to a sharpening
method that was used with film before digital
editing was an option. In that method, a negative
that needed to be sharpened was duplicated. The
duplicate negative was intentionally created just
a bit out of focus. The two negatives ó the
original and the new one ó were then sandwiched
together slightly out of registration and then
printed. The effect increased contrast around
edge detail and made the resulting print look
sharper. This is the same way the USM and the
Smart Sharpen filters work.
The Unsharp Mask dialog box, shown below, is found in the Filter menu (choose
Filter > Sharpen > Unsharp Mask). This filter
doesnít detect edge detail per se; instead it looks
for pixels that have different tonal values than
surrounding pixels. It then increases the contrast
of those surrounding edge pixels, causing the
lighter pixels to get lighter and the darker pixels
to get darker, creating the sharpening halos I
mentioned earlier. The sliders in the USM dialog
box are used to control the size of these halos.
Hereís a closer look at the controls:
Note: You may notice that there are two other
sharpening filters in the Sharpen menu, named
Sharpen and Sharpen More. One would think
that these are the main sharpening tools, but
they arenít. They are blunt instruments that canít
be controlled. In the many years that Iíve been
using Photoshop, Iíve never used either one.
- Amount. The Amount slider is used to
control the amount of contrast between
differing pixels, which affects edge contrast.
Higher values equal more contrast and
lower values equal less contrast.
- Radius. The Radius slider is used to
determine the number of pixels that are
changed when the filter sees tonal variation.
Higher values increase the size of the halos,
causing the sharpening to be obvious.
Because of this, the Radius slider is the
most important slider in this dialog box.
Exercise caution when using it because too
high of a value creates sharpening halos
that are noticeable. To high of a Radius
value combined with a high Amount value
causes the image to look oversharpened. Keep in mind that this value is going to
vary depending on the subject matter. A
lower value works best with photos rich in
edge detail, while a higher value can be
used for photos that donít have as much
detail in them.
- Threshold. The Threshold slider is used to
determine how different in tone the
surrounding pixels need to be before
theyíre considered edge pixels, causing
them to be sharpened. For example, a value
of 5 affects only neighboring pixels that
have a tonal difference of 5 units or more
(on a scale of 0 to 255). The default value
of 0 causes all pixels in the photo to be
Tip: Apply creative sharpening to a duplicate image
layer in the master layered file. This insures that
you can undo any sharpening later by
discarding the layer.
Using the Unsharp Mask requires a bit of a
balancing act among these three sliders. The
best way to understand how theyíre used is to
take the USM filter for a test drive. Follow these
- Download High_Desert_Flower.tif and zoom to 50
percent. This photo has lots of edge
detail on the main subject, with little
edge detail in the background. Remember that the USM filter, like the
rest of Photoshopís filters, only affects
the currently selected layer.
- Choose Filter > Sharpen > Unsharp
Mask. The Unsharp Mask dialog box
- Type 200 for Amount, 2.0 for Radius,
and 10 for Threshold, as shown below. Notice how much sharper
all of the edge detail becomes.
- Change the Amount value to 300. This
oversharpens much of the edge detail on
the flower and makes the image too
Tip: Though the USM dialog box has a preview
window, you wonít be using it. Itís much better
to use the actual image for evaluation purposes.
So go ahead and drag the dialog box to the side
so you can get a good look at the flower.
- Now increase the Threshold setting to
25 and notice that the sharpening
tapers off. This is especially noticeable
in the middle of the crown of the flower
where there are so many similar colors.
Thatís because only edge pixels with a
tonal difference of 25 or more are
- Increase the Amount value to 300. The
sharpening increases, but itís still more
subtle than the Step 2 setting.
- Now increase the Radius value to 4. Notice how much this small adjustment
affects the flowerís edge detail. Itís
beginning to look too crunchy, which
means itís becoming over-sharpened.
- Decrease the Amount value to 200. The
crunchiness is reduced, bringing the
edge contrast back into line. As you can
see, there isnít necessarily an exact set
of sharpening values for this image
because of the way these settings affect one another. If this photo were being
printed, it would benefit from the
settings in Step 3 or Step 8. Something
else to notice here is that the out-offocus
bee is still out of focus, even
though its edges are sharpened.
I find that low Radius and Threshold settings and
higher Amount settings are usually the best place
to start when using the Unsharp Mask. In the
previous exercise you began with 200 for Amount
for this 6 ◊ 9 photo. If the photo were larger, then
a higher starting Amount value (such as 300 for
an 11 ◊ 14) would be appropriate.
Then adjust the Radius and Threshold values to
match the subject content of the photo.
When the sharpening is complete, take one
more look at the tonality and contrast of the
image. Thatís because large amounts of
sharpening affect tonality and contrast. If youíre
using adjustment layers for managing the tones,
make any further adjustments to them before
flattening the file and/or saving it.
Tip: Sometimes sharpening causes a color shift.
When this happens, itís easy to fix. If the
sharpening is applied to a duplicate layer,
change the layerís blending mode to
Luminosity. If the sharpening is applied to the
main image layer, choose Edit > Fade and
change the Mode to Luminosity in the Fade
dialog box. (Just remember that Fade must be
the very next step after sharpening is applied.)
Using the Smart Sharpen Filter
One of Photoshopís newer filters is the Smart
Sharpen filter introduced in version CS2. This
filter is considered smart because it treats
various regions of the image differently based on
the content of those regions. The Smart Sharpen
filter attempts to sharpen only the areas of the
image that have detail without affecting areas
that donít. This is different from the USM filter
that affects all areas of the image equally. The illustration below shows the Smart Sharpen dialog box.
Notice that this dialog has Basic and Advanced
modes. The difference is that the Shadow and
Highlight tabs are added in the Advanced mode.
This dialog box doesnít have a Threshold slider
because it isnít needed. It also has some controls
that arenít in the USM dialog box.
Take a closer look:
- Amount. This slider is used to control the
amount of contrast between differing pixels,
which affects edge contrast. Higher values
equal more contrast and lower values equal
less contrast. It functions the same as the
sliders in the Unsharp Mask.
- Radius. This slider is the same as the
Radius slider in the Unsharp Mask dialog
box. Itís used to determine the number of
surrounding pixels that are changed when
the filter sees tonal variation.
- Remove. This is a cool feature that adjusts
the way the filter works, depending on the
problem. The pop-up menu has three
options: Gaussian Blur, which is the same
algorithm used by the USM filter; Lens Blur,
the best choice for most digital camera files;
and Motion Blur, which attempts to
compensate for blur caused by motion
during the exposure. When Motion Blur is
selected, the Angle setting is activated. This
allows you to input the direction of the
motion that caused the blur. For example, if
the blur is from a sideways motion during
the exposure, use a value of 0.
- Advanced. Selecting this radio button gives
you more control by allowing you to work
with the shadows and highlights
independently of the rest of the image. It
adds two new tabs to the dialog box,
Shadow and Highlight. The figure below shows
the Shadow tab, which is identical to the
Highlight tab. You can use Fade Amount to
adjust the amount of sharpening and Tonal
Width to restrict your adjustments to the
shadows with the Shadow tab, and to the
highlights with the Highlight tab. This is
quite useful when you have lots of noise in
the shadows that you donít want to
- More Accurate. Selecting this option
provides a more accurate sharpening effect,
but the process takes longer.
Note: The only thing I donít like about this filter is that
the dialog box is huge, which can make it hard
to see the image while using the filter ó
especially when working on a computer with a
smaller display. Because I donít use the
dialogís display, I scoot the dialog to the left
until I canít see the dialogís display, freeing up
more room for viewing the image.
Sharpening for Output
In Step 1 of the previous exercise, I asked you to
zoom to 50 percent before using the USM filter.
There are two reasons I specified that zoom
ratio. The first reason is that historically,
Photoshop does the best job of drawing the image onto the screen with zoom ratios that are
multiples of 25 percent. This has changed with
the introduction of OpenGL image processing in
Photoshop CS4. When OpenGL is in effect, the
screen is drawn with equal accuracy at any zoom
level. However, if youíre using Photoshop CS4,
but your system doesnít support OpenGL, then
this wonít be the case for you.
The second reason I specified 50 percent is
because it is the zoom ratio that usually comes
closest to approximating the actual size of the
printed image on your screen, while meeting the
multiples of 25 percent rule I describe previously.
One would think that zooming to 100 percent would display the image at its actual size.
However, because a computer monitor isnít
capable of displaying an image at 300 ppi, it has
to spread the pixels out to the resolution it can
display ó usually between 70 and 90 ppi.
(Thatís why 72 ppi is a common resolution for
photos intended for the Web.) This causes a
photo with a resolution of 300 ppi to look bigger
on the computer monitor than the actual print. If
youíre viewing at 100 percent while sharpening,
you probably will be disappointed in the results
because your preview doesnít match reality.
Youíre seeing the photo at a much larger size
than the final output size.
The optimal zoom ratio can vary from system to
system. Hereís how to find out which zoom ratio
is closest to the actual size for your particular
- Choose View > Rulers to turn on the
rulers. The illustration below shows a photo with
the rulers displayed. If your rulers are
already turned on, you donít have to do
- With the Photoshop rulers showing,
hold a real ruler up to the screen while
zooming the image using the keyboard
shortcut presets (Command++/Ctrl++ to zoom in
and Command+Ė/Ctrl+Ė to zoom out). When
Photoshopís ruler and the real ruler
match, the file is displayed at its actual
size. If OpenGL isnít functioning on your
system, you want a multiple of 25
percent. Try 25 percent and 50 percent
to see which is closest to reality. On all
of my monitors, 50 percent is a little
bigger than reality and 25 percent is a
little smaller. I use 50 percent because
an image that displays a little bigger is
easier to look at and evaluate. If OpenGL
is functioning, you may find that 33
percent, the preset between 25 percent
and 50 percent, comes closest.
Note: When sharpening for the Web, zoom to 100
percent to display the image at actual size
because the output is intended for a computer
Following these guidelines helps insure that the
sharpening you see on your screen more closely
matches the final output size. However, be
advised that there are a couple of other variables
that come into play when adding output
- Display versus Print. Even in a perfect
world, the sharpness shown on a monitor
wonít always translate to printed output.
Thatís because the way a computer displays
an image is different than the way the
image looks on paper. In fact, different
monitors often look different from one
another. When I first switched from a
CRT monitor to an LCD flat panel monitor I
noticed that everything looked sharper on
the new monitor. Thatís because of the
resolving power of this newer style of LCD
monitors. I had to make a mental
adjustment to compensate for this.
- Printing Processes. Different kinds of
printers and printing paper affect the way
an image looks. Prints on glossy paper
always look a little sharper than prints on
matte. Some inkjet papers, such as fine-art
papers, are very absorbent and really soak
up the ink, which diminishes the effects of
- Size Matters. Sharpening is dependent on
the dimensions of the print. Thatís why itís
important to do all final cropping and sizing
before output sharpening is applied.
The thing to take away from this section is to
experiment with your intended output process
until youíre comfortable predicting how your
computerís display translates to a printed image.
Make some prints and compare them to the
images on your monitor until you feel comfortable
predicting any discrepancies between the way
the monitor displays the image and the way it
looks when printed.