Adobe InDesign CS3 - Manual (Page 585)

INDESIGN CS3
User Guide
578
InDesign also has overprint simulation, which is useful for simulating the effects of overprinting spot and process
inks on a composite printing device.
Black ink applied to text or native InDesign objects is overprinted by default to prevent misregistration of small
black-type characters positioned over color areas, or of color areas outlined with black lines. You can change black
ink settings using Appearance Of Black preferences.
Your design workflow may require a certain color to be set to overprint. For example, you want to print all the text
in your publication in a specific color. Consider the following options:
• Create an object style that uses the spot ink as the fill or stroke with a matching overprint fill or stroke.
• Create a separate layer for objects that contain your spot color and assign them to black.
• Create a composite PDF and change overprint settings within the PDF.
• Assign overprint settings in your RIP.
• Apply overprint settings to an image or object and add it to your library, or edit a placed file in its original appli-
cation.
See also
“Previewing color separations” on page 581
“Simulate overprinting of spot inks” on page 580
Determining when to overprint manually
Automatic trapping in InDesign—either as built-in trapping or Adobe In-RIP Trapping—nearly eliminates the need
for manual overprinting. However, manual overprinting can be an effective solution in the rare cases when you can’t
use automatic trapping.
Use the following guidelines to determine whether or not to use overprinting:
• Consult with your service provider to see if their output devices support manual overprinting.
• Overprint when the artwork doesn’t share common ink colors and you want to create a trap or overlaid ink effects.
When overprinting process color mixes or custom colors that don’t share common ink colors, the overprint color
is added to the background color. For example, if you print a fill of 100% magenta over a fill of 100% cyan, the
overlapping fills appear violet, not magenta.
• Don’t overprint when using a stroke to trap two process colors. Instead, you specify a CMYK stroke color that uses
the higher value from the corresponding inks in each original color.
• Make sure that you and your prepress service provider agree on when and how to overprint manually, because
doing so will significantly affect trapping options specified in the Print dialog box. Overprinting is supported by
most, but not all, PostScript Level 2 and PostScript 3 devices.
Overprint a stroke or fill
You can overprint strokes or fills of any selected paths using the Attributes panel. An overprinted stroke or fill doesn’t
need to be trapped, because overprinting covers any potential gaps between adjacent colors. You can also overprint
a stroke to simulate a trap (by overprinting a color you’ve manually calculated as the proper combination of two
adjacent colors).