e - Ken Gilbert

Technique Using Curves to control contrast
SOFTWARE USED Adobe Photoshop CS4
SKILL LEVEL
TIME TO COMPLETE 30 minutes+
Before
PHOTOGRAPHERS face many challenges,
but probably the biggest is contrast, especially
with digital capture because there are times when
you just can’t record a full tonal range in a single
shot – even if the contrast in an image does fall
within the sensor’s dynamic range. Sometimes,
getting the exposure ‘right’ for the subject means
you have to accept that other areas will appear
lighter or darker than you want.
This image is a case in point. Although the
exposure is acceptable for the subject, the
background is too light and contrasty, while the
contrast in the subject could actually do with a
slight boost. The problem is a single adjustment
can fi x only one of these problems – you simply
Localised
contrast
control
G i hChris Ch i Gatcum G h shows h hhow
to alter the contrast in
an image using Curves
adjustment layers and
their associated masks
can’t reduce and increase contrast simultaneously.
In the traditional darkroom, the answer is (with
multigrade paper) to use different grades of fi lter,
from an ultra-low-contrast 00 to a high-contrast
grade 5, for specifi c parts of an image, so a highcontrast
area in the negative could be tackled with
a low-contrast fi lter, and vice versa. This method
translates directly to the digital darkroom, only
now you have much greater control and can fi netune
the result until it’s precisely what you want.
The key to this is Curves adjustment layers and
associated masks, with the former allowing you to
make the ‘non-destructive’ changes to the image,
while the latter enables you to pinpoint precisely
where those adjustments will take effect.
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