CHAPTER 10
962
Document Interchange
10.10 Prepress Support
This section describes features of PDF that support prepress production work-
flows:
•
The specification of
page boundaries
governing various aspects of the prepress
process, such as cropping, bleed, and trimming (Section 10.10.1, “Page Bound-
•
Facilities for including
printer’s marks,
such as registration targets, gray ramps,
color bars, and cut marks to assist in the production process (Section 10.10.2,
•
Information for generating
color separations
for pages in a document (Section
•
Output intents
for matching the color characteristics of a document with those
of a target output device or production environment in which it will be printed
•
Support for the generation of
traps
to minimize the visual effects of misregis-
tration between multiple colorants (Section 10.10.5, “Trapping Support”)
•
The
Open Prepress Interface (OPI)
for creating low-resolution proxies for high-
resolution images (Section 10.10.6, “Open Prepress Interface (OPI)”)
10.10.1 Page Boundaries
A PDF page may be prepared either for a finished medium, such as a sheet of
paper, or as part of a prepress process in which the content of the page is placed
on an intermediate medium, such as film or an imposed reproduction plate. In
the latter case, it is important to distinguish between the intermediate page and
the finished page. The intermediate page may often include additional
production-related content, such as bleeds or printer marks, that falls outside the
boundaries of the finished page. To handle such cases, a PDF page can define as
many as five separate boundaries to control various aspects of the imaging
process:
•
The
media box
defines the boundaries of the physical medium on which the
page is to be printed. It may include any extended area surrounding the
finished page for bleed, printing marks, or other such purposes. It may also