Graphics Programs Reference
In-Depth Information
Grayscale
A grayscale image uses different shades of gray
to represent image details. For example, an 8-bit
image is represented by 256 levels of gray (see
“Bit Depth” later in this chapter). Likewise, a
16-bit image would show 65,536 levels of gray
(a substantial improvement, but it requires an
output device that can utilize the data). When
creating grayscale images, it is important to per-
form test prints with the output device and paper
to see how contrast is maintained.
Duotone
A duotone image can actually be monotone,
duotone, tritone, or quadtone. Grayscale images
that use a single-colored ink are called
mono-
tones.
Duotones
,
tritones
, or
quadtones
are grayscale
images printed with two, three, or four inks,
respectively. Using both black and gray ink
to represent the tonal values, duotones create
better-quality printed grayscales. This mode
should be used when you know the printer is set
up specifically to handle the job. If you just want
the look of a duotone, you can create that look by
working in RGB mode and using the Black and
White adjustment layer.
The most popular form of
duotone is a sepia-tone image
(often seen in historical prints).
In modern times, a designer
may use a duotone for style
purposes or to save money by
using fewer inks.