Section III Digital Postprocessing
422
Cleaning up the Image
Despite the most careful cleaning of a
negative before printing in the conventional
darkroom, at least a few small white dust spots
are likely to turn up on the final print. These
must be eliminated by the use of dye solutions
and a very fine-pointed brush. The process,
called spotting, is tedious and takes some practice
to achieve acceptable results. The process is
described in Chapter 21, Advanced Printing.
The digital darkroom makes the spotting
task much easier, but careful cleaning of scanned
materials is still necessary to minimize the
problem. When scanning from prints, the glass
of the flatbed scanner should be inspected and
cleaned if necessary; negatives and slides should
be dusted with a soft (preferably antistatic) brush
before being inserted in the film scanner.
Spotting may also be necessary on images
captured with a digital SLR camera: when the
camera body is opened to change lenses, dust
and lint particles can enter and settle on the cover
plate of the sensor. The particles show up as dark
spots when the image is displayed. They are
especially noticeable in areas of light, continuous
tone such as the sky or an expanse of snow or
sand.
Spotting is done with the
Clone Stamp
tool,
which is used to copy (clone) a small area of the
image and place it over the dust spot. The size
of the copied area and the nature of the copied
information (hard- or soft-edged and the degree
of opacity) can be varied to suit the situation. The
working size of the
Clone Stamp
tool is set by
choosing a brush size from the
Brushes
palette;
for spotting work, a fairly small soft-edged brush
is normally used.
Figure 15-41 shows a portion of a scanned
antique image that requires spotting. Note
that only a portion of the image is visible—all
spotting work should be done with the image
at the full size (100 percent) setting. This allows
you to see what the image will look like when
printed, so that defects can be identified and
corrected. Spotting should be done systematically,
beginning at one of the image corners and
proceeding in steps until the entire image has
been processed. The
PAGE UP
and
PAGE DOWN
keys allow you to step through the image
vertically; combined with the
CTRL
key, they
allow horizontal stepping.
A major drawback to using the preceding
methods for monochrome conversion is that they
are destructive: once the image has been saved,
the change cannot be reversed. The best choice
is the use of a
Black & White
adjustment layer.
Adjustment layers are nondestructive, meaning
the images can be saved and closed, then opened
again, and the changes removed to bring the
image back to its original state.
Like
Channel
Mixer, the
Black & White
adjustment layer allows you to adjust color sliders
and try different combinations to find the best
monochrome conversion. Instead of the three
(red, green, and blue) color sliders in the
Channel
Mixer, however, the
Black & White
adjustment
layer has six: reds, yellows, greens, cyans, blues,
and magentas. See Figure 15-40.
An alternate adjustment method to the color
sliders is the
Target adjustment
tool. Place the
tool cursor on an area of tone you wish to alter.
Then, click the mouse button and drag the tool,
observing the changes on the image preview.
Once you are satisfied with the conversion, close
and save the image. If you later wish to try a
different set of adjustments, open the file and
click on the
Black & White
adjustment layer in
the
Layers
palette. You can then make additional
changes and resave the file.
Figure 15-40. A
Black & White
adjustment layer is easily
created by clicking its icon on the
Adjustments
panel.
The monochrome conversion can be altered by using the
color sliders, or by clicking on the
Target
adjustment tool
and placing it on an area to be altered.
Target
adjustment
tool