Adobe INDESIGN 2.0 - USING HELP Help Manual page 323

Adobe InDesign Help
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Keep in mind that the trapping solution you choose must work well with the color output
workflow you're using, such as PostScript or PDF. (See
page 414.)
Automatic trapping
InDesign can automatically trap color documents with its built-in trapping engine, and
can also take advantage of the similar but more powerful Adobe In-RIP Trapping engine
available on Adobe PostScript output devices that support Adobe In-RIP Trapping.
Both trapping engines can precisely calculate and apply any necessary adjustments to the
edges of both type and graphics throughout your document. They can apply effective
trapping techniques to different parts of a single object, even if text or an InDesign object
overlaps several different background colors. Trapping adjustments are made automati-
cally, and you can define trap styles to address the trapping requirements of specific
page ranges. The effects of trapping are apparent only on color separations generated by
a trapping engine; you cannot see the results on-screen within InDesign.
The trapping engine decides where to trap by detecting contrasting color edges, and then
creates traps based on the neutral densities (lightness or darkness) of abutting colors, in
most cases by spreading lighter colors into adjacent darker colors. The trapping settings
you specify in the Trap Styles palette modify the trapping engine's results.
Comparing Adobe In-RIP Trapping and built-in trapping
While built-in trapping and Adobe In-RIP Trapping are quite similar, they can produce
significantly different output from the same document. For best results, read the following
sections and learn about the differences between the two trapping engines.
Requirements for trapping
To trap documents using either the InDesign built-in engine or the Adobe In-RIP Trapping
engine, you need the following software and hardware:
A PPD (PostScript Printer Description) file for a printer that supports Adobe In-RIP
•
Trapping. You must select this PPD by using the operating system driver. (See
up a PPD" on page
An Adobe PostScript Level 2 or later output device that uses a RIP that supports Adobe
•
In-RIP Trapping. To find out if a PostScript output device supports Adobe In-RIP
Trapping, contact the manufacturer or your prepress service provider.
General differences between built-in and Adobe In-RIP Trapping
The following are some of the features that differ between built-in trapping and Adobe In-
RIP Trapping:
Composite color workflow. With built-in trapping, you can separate a document by
•
using InDesign or in-RIP separations. To use Adobe In-RIP Trapping, you must use In-RIP
separations.
Trap widths. Built-in trapping limits trap widths to 4 points, regardless of the value you
•
enter for the trap widths. For larger trap widths, use Adobe In-RIP Trapping.
Additional differences between built-in and Adobe In-RIP Trapping are described in the
following sections.
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386.)
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Trapping Color
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