Adobe ILLUSTRATOR 6.0, Online Manual, Page: 649 / 893

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Printing: an overview
When you print a document, the Adobe
Illustrator program sends it to a printing
device, either to be printed directly onto
paper or to be converted to a positive
or negative image on film. In the latter
case, the film can then be used to create
a master plate for printing by a mechan-
ical press.
The simplest types of images, such as a
page of text, use only one color in one
level of gray. A more complex image is
one whose color tones vary within the
image. This type of image is known as a
continuous-tone image. A placed image,
such as a scanned photograph, is an
example of a continuous-tone image.
To create the illusion of a continuous
tone, the image is broken down into
a series of dots. This process is called
halftoning. Varying the size and density
of the dots in a halftone screen creates
the optical illusion of variations of gray
or continuous color in the image.