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HOW UNSHARP MASKING
SHARPENS IMAGES! part 2
Examples of Images with and without
USM
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This
image
which was scanned without Unsharp
Masking appears very smooth and
colourfu,l but unfortunately is very soft and lacks definition. |
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The
same
image with very high USM applied and no "smoothing".
Consequently
it is so sharp that it appears to be "breaking up". The
fringes
are so large that they appear to be taking over! In
certain areas the fringes appear to cause a colour shift. The
lack of smoothing
is
evident in the amount of "grain" or "noise" which is being picked up
and enhanced by the sharpening, particularly in the green of the
background cloth and in the white card. |
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This
image has a
moderate amount of USM Sharpening applied. It is still
sharp however. You
may notice that the fringes are not necessarily white and black, but
may be better described as "light" and "dark". |
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The pictures
below further illustrate
the effect USM has. They were
scanned (in RGB) on a
brand new Fujifilm Celsis drum scanner at 150% enlargement at 300
dpi.
The
images have been enlarged and converted to 72 dpi for the Web.
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The
left image has absolutely no USM and whilst it is much too soft it does
actually
have all
of the detail present.
The
centre image has minimum USM: Sharp 1, Smooth 2, Threshold
10. It
is noticeably sharper, and could be used if the client requested
"minimal or no sharpening." It could be further
sharpened
in PhotoShop if required.
The right
image has a higher level of sharpness: Sharp 5, Smooth 2,
Threshold
5. This is probably too much Sharpness when scanning a good
transparency with a modern Celsis scanner.
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