User Guide

Printing 399
In addition, because different types of paper absorb inks in different ways,
the characteristics of your paper and the press also determine the screen ruling
you should use.
When setting the screen ruling for grayscale images, the maximum number of
grays possible in an image is 256. Increasing the screen ruling decreases the
number of grays available. The maximum number of grays that can be used in
Gradient fills or blends depends on the capability of your final output device and
the maximum steps value.
For color images, follow the guidelines in the table for specifying a screen ruling:
For grayscale images, follow the guidelines in the following table:
Applying halftone settings to selected objects
If you’ve included screened objects in your artwork, you can select halftone
settings for selected objects, to print those objects at halftone settings that differ
from those applied to the document as a whole.
You can override object-level halftone settings when choosing Separations options
in the Print Setup dialog box. For more information, see “Setting separations
options” on page 396.
Screen Ruling (lpi) Type of Printing
65 to 85 Newspapers or point of purchase displays on
absorbent, uncoated stock
90 to 133 Business publications, freestanding inserts, or
newspaper coupons on coated stock
133 to 150 Menus, travel publications, or yearbooks on
medium- to high-quality coated stocks
Above 150 Coffee table books, museum-quality prints, fine art
reproductions, automobile promotional brochures,
or annual reports on high-quality coated stock
running on highly accurate presses
Resolution (dpi) Screen Ruling (lpi) Number of Grays Printed
300 53 to 60 26 to 33
600 71 to 85 51 to 72
1200 or 1270 65 to 128 89 to 256
2400 or 2540 90 to 150 256
3386 or 3600 150 to 300 128 to 256