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Chapter 15 Digital Darkroom Basics
The digital techniques, like their conventional
counterparts of burning and dodging, cannot
create texture and detail where none is available.
If highlight areas are “blown out” to pure white
by overexposure, burning in can do nothing
more than create a featureless and unattractive
gray tone. Similarly, dense black underexposed
shadow areas can be lightened, but will also be
without any detail or texture.
Altering Contrast
Altering the relationship of shadow and
highlight, or contrast, within a photo is one of the
basic operations of both the conventional and the
digital darkroom. Whether made from a negative,
a scan, or a digital camera file, a straight print
(unaltered image) is seldom totally satisfactory.
The tonal range may be too narrow, resulting in
a flat and dull image, or too wide, producing a
harsh and too-contrasty print.
In the conventional darkroom, the overall
contrast of the print is adjusted by selecting a
different grade of paper or a different filter (when
using variable contrast papers). For a flat image, a
“harder” (higher-numbered) paper grade or filter
is chosen; an overly-contrasty image would call
for a “softer” (lower-numbered) paper or filter.
Both papers and filters are limited in the contrast
grades offered. Papers range from grade 0 (very
soft) to grade 5 (very hard), while filters may be
found in half-step increments from 00 to 5.
The digital darkroom, however, permits use
of an infinite range of contrast alterations. There
are two basic methods for changing contrast: the
Brightness/Contrast
command, and the
Curves
command. Both are available as adjustment
layers, allowing them to be applied without
affecting the pixels of the
Background
layer
(original image).
Brightness/Contrast
is simple and easy to
use: sliders allow adjustment of either contrast
from 0 to 100 (increase) or 0 to –100 (decrease).
Control is not very precise, however, since sliders
are difficult to adjust in small increments.
Curves, Figure 15-27, is more versatile. Its
tone graph is initially presented as a straight
diagonal line, representing the gradation from
darkest value (at lower left) to brightest value (at
upper right). Using the mouse, a graph curve can
be constructed that is reflected by value changes
in the image. If the
Preview
box is checked (the
usual configuration), changes can be observed on
the monitor as adjustments are made.
Figure 15-26. Controls for the
Dodge
and
Burn
tools
have the same options: adjusting the intensity of the
effect on a scale of 1 to 100, and a selection of affecting
the shadow, midtone, or highlight values. In this case,
a large soft brush is being used at a low intensity
(exposure) of 10 percent to “burn in” the washed-out
looking vegetation behind the subject.
Burn tool selected
Figure 15-27. When the
Curves
adjustment layer is
first opened, the tone curve is shown as a straight line
The lower left end of the curve represents the shadow
values; the upper right end, highlights.