
ABOUT NOISE
About Noise
Electronic noise is inherent to all RAW images, but its cause
varies. It is more apparent in some images, and barely notice-
able in others. Higher ISO values will enhance this eect, as will
underexposure or long exposure. Process over-sharpening will
also enhance electronic noise.
The noise in the detail of Figure 9-1
(enlarged to 400%) is a result of shooting at
a high ISO setting. Mark Richards captured
this rare shot of the inside of San Quentin for
People magazine by boosting the sensitivity
of his digital camera to 1600 ISO. He got the
exposure settings he wanted, but obviously
at a price in image quality.
On the other hand, the noise in the detail
of Figure 9-2 (enlarged to 200%), taken at
night at a normal ISO, is due to a relatively
long exposure (1/3 second) and it’s mostly
apparent in the dark sky.
Of course, noise isn’t necessarily bad.
As Luis Delgado Qualtrough, a fine art
photographer puts it, “noise gives an
image dimension—and authenticity.” Luis
came across the old painting in Figure 9-3
hanging on the wall in a very dark room
at an old hacienda in Mexico. Setting his
digital camera to 1600 ISO, Luis managed to
get the shot without a tripod. Luis chose to
leave the noise in the image, to emphasize
the impressionist style of the painting. The
final shot hangs in a Danish museum.
In any case, it’s relatively easy to remove ...