Graphics Programs Reference
In-Depth Information
PDF/X
The PDF/X Standard is a family of ISO standards for graphics exchange in the printing
industry, the latest of which is PDF/X-5 (ISO 15930-8:2010). It defines a number of
restrictions:
• All fonts must be embedded
• All image data must be embedded
• Cannot contain sound, films or non-printable annotations
• No forms
• No JavaScript
• Limited compression algorithms
• No encryption
and a number of extra requirements:
• The file is marked as PDF/X with the subversion (e.g., PDF/X-5)
• Bleed, trim and/or art boxes are required, in addition to the normal page size. These
boxes define the size of the media, the printable area, the final cut size, and so on.
• A flag is set if the file has been
trapped
. Trapping is the process of creating small
overlaps between graphical objects to mask registration problems in multiple color
printing processes.
• The file must contain an
output intent
, containing a color profile describing how it
is to be printed.
Version Summary
PDF is fully backward compatible (you can load a PDF version 1.0 document into a
program designed for PDF 1.7) and mostly forward compatible (programs written for
PDF 1.0 can normally load PDF 1.7 files). Forward compatibility is ensured because
readers ignore content they don't understand—it's only when new compression meth-
ods or object storage mechanisms are introduced that this may be broken. Since PDF
1.5 in 2003, such changes have been minimal. PDF versions and their features are
summarized in
Table 1-1
.
Table 1-1. Functionality in PDF versions 1.0 to 1.7 Extension Level 8
PDF version
Acrobat Reader
version
Launched
Summary of new features
1.0
1.0
1993
First release.
1.1
2.0
1996
Device independent color spaces, encryption (40-bit), ar-
ticle threads, named destinations, and hyperlinks.
1.2
3.0
1996
AcroForms (interactive forms), films, and sounds, more
compression methods, Unicode support.
