8.5

The commands you use to create overprinted strokes for traps will vary between illustration
applications. See the documentation for that application for instructions on creating strokes
and overprints.
Creating and using a rich black
Printers and graphic designers often use rich black to create a deeper, darker black to achieve
an even, very dark coloration for large areas of ink coverage. A standard rich black is
composed of 100% process black laid over a screened percentage of a process color build.
Because it is composed of more than one process ink, misregistration of rich black on press
is likely. Consequently, QuarkXPress handles trapping differently for rich black. If an
object color spreads into a rich black background, all process colors except process black
will spread according to the value specified in the Auto Amount field (Edit > Preferences >
Trapping pane). If the rich black object color is being choked by a background color, then
all process colors except for process black will choke. This special trapping process is used
to keep the background process colors from showing through in the event of misregistration.
QuarkXPress applies a rich black trap only when the percentage of process black in a rich
black is greater than or equal to the percentage entered in the Overprint Limit field (Edit >
Preferences > Trapping pane).
QuarkXPress applies a rich black trap only when a 100% shade is applied to a rich black
color.
Understanding flattening and production issues
Since PostScript has no concept of transparency, flattening is the process of simulating
transparency by altering page elements to produce the intended design. Flattening occurs
only in the print stream — as items are fed to the print engine — so your QuarkXPress
layouts are never actually modified. In QuarkXPress, flattening works as follows.
First, boxes are decomposed, transparent elements are identified, and relationships between
discrete shapes (including text outlines) are deconstructed. Regions that do not have to
be rasterized are filled with a new color that is created by merging existing colors. (None
and 0% opacity areas do not need to be flattened except when used for blends and pictures.)
Regions that need to be rasterized result in clipping paths. (Semi-opaque pictures, drop
shadows, semi-opaque blends, and semi-opaque items that overlap page elements must
be rasterized.)
The settings in the Transparency pane of the Print dialog box (File menu) control the
output resolution of page elements that are rasterized due to transparency effects or drop
shadows. For more information, see "Transparency pane."
In general, when working with transparency relationships, trapping is not necessary. When
trapping does come into play, overprints of opaque items are inherited by paths created
through decomposition; chokes and spreads set for transparent elements are ignored. All
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