|
After
starting Photoshop, click File/Open to open the photo
from the location where you have copied it.
 When
the picture displays on the Photoshop workbench, you can zoom it
as you like. In the upper left corner of the workbench, you can
see a small window with tabs called Navigator and Info.
You can set the zoom rate in the Navigator window. 100% displays
the image in its original size. This does not increase or decrease
the real dimensions of the photo, you just see it this size in the
application. You may want to use a 100% zoom value even if
the picture doesn't fit on the screen, so that you can see the borders
of the sharpening area exactly.
 You
may use different filters for sharpening. These can be found in
the File/Filter/Sharpen submenu. In the Photoshop
version I use (v7.01) you can choose 4 different filters called
Sharpen, Sharpen Edges, Sharpen More, and Unsharp Mask.
The first three does sharpening in a predefined way so they should
only be used for very quick sharpening jobs that need to be done
in a few seconds. You can achieve the best results by using the
filter Unsharp Mask that can be set in relatively different
manners. In the following section, we provide a more detailed description
of this filter. A few words about the other sharpening procedures:
Sharpen does a mild automatic sharpening on the whole picture.
Sharpen Edges sharpens the finer edges in the photo. Sharpen
More provides a stronger sharpening on the image
Now let's get back to Unsharp Mask. After clicking this menu
item, a small window appears with the preview of the image in the
upper left corner for checking the results of your actions in advance.
Set zoom rate to 100% to see the photo in its original size. Make
sure that Preview is selected in the upper right area. It
is selected by default. You can also monitor the sharpening procedure
outside the window, on the main picture.
At the bottom of the window you can see 3 sliders. Amount sets the
sharpening value from 0 to 500%. Radius specifies the width of the
sharpening relative to the detected edges. Lower values result in
sharpening the tiny, finer details while higher ones apply it to
the rougher, broader edges. The value can be set from 0 to 250 pixels.
Threshold sets the limit under which the application decides
that an area should be sharpened. The value can be set from 0 to
255 pixels. When set to 0, the sharpening effect will be applied
to any area that can be detected as an edge. The higher the value,
the smaller the actually sharpened area. You may find this a bit
confusing at first, but you don't need to learn the text by heart!
Try the functions repeatedly, and after a while you will feel which
value you should change.
Let's
see an example. You have loaded the portrait of your little favorite
and opened the Unsharp Mask window. You can see that the
fur appears in tiny, fine details in the picture. You want to emphasize
these details more. Set Amount to 500% at first so that you
can see the effect of sharpening in its wholeness. You will lower
this value to refine the effect later. Leave Threshold at
0 to have the sharpening applied to the whole picture. Now try
Radius! If you drag the slider towards higher values, you can
easily see the result of the effect. As the image contains finer
details, too high values cause it to "fall apart": Unrealistic,
rough edges appear, followed by enormous contrast. You only need
to emphasize the finer details but keep the natural character of
the photo. In this case, the very fine Radius value of 0.3
leads to a result pleasing to the eye. 0.4 is already a bit excessive.
It can be used as a rule of thumb that pictures containing many
details can be sharpened nicely by using an Amount of 500%
and a Radius of 0.3 or even 0.2. In this particular case
you can keep 0.3 but reduce Amount to about 300% and Threshold
to 2, as the aggressive, too light edges look disharmoniously even
at a Radius of 0.3. These settings can be generally used
for photos of furry animals or, for example, landscapes. When dealing
with even finer details, a Radius of 0.2 and an Amount
of 400 to 500% may lead to a nicer result. Because of the silvery
nature of the cat's fur, a Radius of 0.3 is not very irritating.
Generally, keep Threshold low, you may even leave it set
to 0.
Keep in mind though, that sharpening smaller details may not only
enhance the characteristics of the fur but also cause the appearance
of small grains called noise. Your basic guideline for sharpening
is: BE CAUTIOUS!
If the image contains fewer details (as with a photo of a building
or a human silhouette, where you don't want to emphasize the small
details) you may want to set Radius to 1 and leave Amount
on a low setting of about 50 to 100%. This way, relatively broader
edges, silhouettes will be sharpened but finer details and noise
won't.
In
the next sharpening lesson, you will get acquainted with more complex
procedures. Until then, have a good time with Unsharp Mask!
Without sharpening / unsharp mask
|
Digiretus.hu
|
Digiretus.ro|
RSS
