CHAPTER 9 HOW SOFTWARE CHANGES PIXELS BY THE NUMBERS^153
The digital darkroom masks off the areas
that have a balance of color tones and
leaves these areas alone.4
To the remainder of the photo, the software
applies the routines it would use for an
underexposed photo, adding the same
amounts to the values for the three colors
that make up the pixels. The higher values
represent lighter shades.5
The result is that the cor-
rectly exposed background
is retained and the under-
exposed subject has come
out of the shadows. Notice,
however, that this correc-
tion still doesn’t manage to
bring out any highlights in
the subject because all
color values are raised
equally. The image of the
girl lacks dynamic
range. For fuller explana-
tions of dynamic range, see
“How Histograms Run the
Gamut” in Chapter 5 and
“How Photoshop Multiplies
a Photo’s Dynamic Range”
in Chapter 9.6