In the last issue we created a chart to show the options for
creating monochrome prints. A chart on the methods of sharpening would be
equally complex and you will be relieved to hear that we are not going to
make you endure another one! The subject of sharpening is discussed
endlessly on web forums and is a frequent topic of questions at the end of
seminars. There is a basic insecurity among photographers that their rival
down the street has a magic sharpening formula that is doing better than
their own method. This insecurity leads to arcane methods of sharpening -
magic angel dust, deconvolution, Gaussian processing and HiRaLoAm are just a
few of the buzz words floating about.
CS4 and, in particular, the new RAW file processing engine has turned the
sharpening world upside down, but more of that in a moment.
Let's start by clearing the fog with a list of facts ('facts' as in things
that everybody agrees upon):
RIGHT: A negative amount of Clarity has been applied to the
left side of the image, the right side has been sharpened normally.
1. Sharpening is the artificial creation of enhanced edges in those parts of
an image where a dark bit meets a lighter bit, typified, for example, where
a bride's dress adjoins her groom's dark suit.
2. Sharpening may be carried out at one or more stages of the workflow,
either in the camera, during image processing, or during image printing.
3. Sharpening is essential in a digital image, will always improve a
well-made image, but will only rarely rescue a fundamentally flawed (fuzzy)
image.
4. Half the world spend their time making their images sharper, the other
half spend their time making them softer and dreamy (actually we made that
bit up!).
5. There is no absolute point that defines a perfect degree of sharpening.
It varies with image size, image viewing distance, image content, viewer's
preference and a host of other technical things. For this reason there is no
universal image sharpening strategy or set of universal parameters.
6. Sharpening can rarely be accurately judged on the computer monitor, you
can 'make do', but the print is the only real way to test things.
Sharpening in camera
If you wish to shoot JPEG images, and not carry out any postcreation
processing, you have to rely on the camera software to do your sharpening
for you. Sharpening in camera is usually a simple choice between (typically)
half a dozen settings (eg none, low, medium low, normal, medium high and
high for a Nikon camera). The setting of the sharpening value can be buried
deep in a camera menu. On a Nikon D200, for example, you have to navigate
through:
Menu>Shooting menu>Optimise Image>Custom>Image Sharpening.
It's hardly a top-line menu item then! The fastest way to determine what
your settings are is probably to look at the metadata in Adobe Bridge.
This is emphasised capitals because it is important. Regardless of what your
camera settings are, your RAW file arrives at your computer unsharpened. If
you don't believe us then open a JPEG 'as a RAW file' and you will see the
sharpening set to zero in the Amount. Open a RAW file in Adobe Camera RAW
and you find a default value of 25. In other words Adobe expects your JPEG
to arrive sharpened in the camera, but your RAW files to need sharpening
when you process them. The reason for this is simple, sophisticated
sharpening requires a lot of computing power, more than is readily available
on most camera systems, so the process has to be delayed until the RAW file
hits the computer!
ABOVE: The metadata will tell you what type and level of sharpening has been
applied by your camera.
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