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About printing
Printing is the process of sending the pages in your document to an output device.
Whether you are providing a multicolored document to an outside service provider or just
sending a quick draft to an inkjet or laser printer, knowing a few basics about printing
makes the print job go more smoothly and helps to ensure that the finished document
appears as intended. To make optimal decisions about printing, you should understand
basic printing principles, including how the resolution of your printer or the calibration
and resolution of your monitor can affect the way your document appears when printed.
Types of printing
When you print a file, the application sends it to a printing device to be printed directly on
paper or on a digital printing press, or to be converted to a positive or negative image on
film, which can then be used to create a master plate for printing by a commercial press.
The application can also convert a document to PostScript for use in printing and prepress
applications. The PostScript file includes full Document Structuring Conventions
comments; an Adobe PDF file converted to PostScript also includes other advanced
information preserved by Acrobat Distiller.
Types of images
The simplest types of images, such as text, use only one color in one level of gray. A more
complex image is one with color tones that vary within the image. This type of image is
known as a continuous-tone image. A digital photograph is an example of a continuous-
tone image.
Halftoning
To create the illusion of continuous tone, images are broken down into a series of dots.
This process is called halftoning. Varying the sizes and densities of the dots in a halftone
screen creates the optical illusion of variations of gray or continuous color in the printed
image. (See
Specifying halftone screen frequency .)
Color separation
Artwork that will be commercially reproduced and that contains more than a single color
must be printed on separate master plates, one for each color. This process is called color
separation. (See
Printing color separations .)
Getting image detail
The detail in a printed image results from a combination of printer resolution and screen
frequency. The higher an output device's resolution, the finer (higher) the screen
frequency you can use. (See
Specifying halftone screen frequency .)
Transparent objects
If the Adobe PDF file contains objects with transparency features that were added in
Adobe InDesign 2.0 or later, Adobe Illustrator 9.0 or later, or Adobe Photoshop 7.0 or
later, the transparent artwork is flattened according to settings you specify in the
Advanced Print Setup dialog box. You can affect the ratio of rasterized images to vector
images in the printed artwork. (See
Controlling transparency flattening .)