To convert an image
to a duotone, you change a bitmap to the grayscale color mode and enhance it
using one to four additional colors, giving the image greater tonal depth.
The following four
variations of the color mode correspond to the number of additional inks:
• Monotone — a grayscale image colored with a single tone
• Duotone — a grayscale image colored with two tones. In most cases, one is
black and the other is colored.
• Tritone — a grayscale image colored with three tones. In most cases, one
is black and the other two are colored.
• Quadtone — a grayscale image colored with four tones. In most cases, one
is black and the other three are colored.
The four color mode
variations. From left to right: the original image, monotone, duotone, tritone,
When you change an
image to a duotone, a tone curve grid that represents the dynamic tone curves
that are used throughout the conversion is displayed. The horizontal plane
(x-axis) displays the 256 possible shades of gray in a grayscale image (0 is
black; 255 is white). The vertical plane (y-axis) indicates the intensity of a
color (from 0 to 100 percent) that is applied to the corresponding grayscale
values. For example, a grayscale pixel with a color value of 25 is printed with
a 25-percent tint of the color. By adjusting the tone curves, you can control
the color and intensity of the tone that is added to an image.
Saving and loading
You can save an
adjusted duotone tone curve and ink settings and then load them for use with
overprint colors display
When you change an
image to a duotone, you can specify the colors to overprint when you print an
image. Overprint colors are used to preserve color integrity when inks overlap.
When you display the image, each color is applied on the screen in sequence,
creating a layered effect.
You can view all
instances in which the colors you choose for the duotone conversion overlap.
Associated with each instance is the color that is produced by the overlap. You
can also choose new overprint colors to see how they overlap.
Duotones will hold
their color ink information when saving to Encapsulated PostScript (EPS),
Portable Document Format (PDF) and CorelDRAW (CDR) file formats. Other file
formats don’t support duotone images.