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Basic Introduction to PDF/X

The PDF/X standard responds to the challenge of ensuring that graphic arts files are written in a way that will reproduce on press exactly as the files' creators intended. As a subset of the Adobe PDF specification, PDF/X is designed for the blind exchange of final print-ready pages, and is one of the most predictable ways to deliver files bound for press.

Why PDF/X?
Using PDF/X-compliant files eliminates the most common errors in file preparation: fonts that aren' t embedded, incorrect color spaces, missing images, and overprinting and trapping issues. These issues don't arise with PDF/X files because, by definition, these standards require that all fonts be embedded, appropriate PDF bounding boxes be specified, and color be correctly and consistently defined. PDF/X-compliant files also must describe the printing condition for which they are prepared.

PDF/X Variants
PDF/X has three variants, PDF/X-1a, PDF/X-3, and PDF/X-4. PDF/X-1a and PDF/X-3 are the most popular PDF/X formats; PDF/X-4 is a new standard, which is expected to be ratified as a CGATS (Committee for Graphic Arts Technologies Standards) and ISO standard in 2007. Click here to learn more details about PDF/X Variants>>

About PDF/X file contents
PDF/X files require certain contents, prohibit others, and leave some open. It's helpful to know what's allowed and prohibited in PDF/X files before creating, preflighting, and correcting them; and when customizing any settings.
Here's what must be included in a PDF/X file:

  • Fonts and images embedded.
  • Page geometry (the trim box and bleed box) defined.
  • Intended printing condition (output intent).
  • Trapping key (Yes = True, No = False) defined.
  • Title, creator, producer, creation, and modification dates.

Here's what's prohibited in PDF/X files:
  • Live transparency, except in PDF/X-4 files.
  • Layers, except in PDF/X-4 files.
  • Encryption (security).
  • Form fields.
  • Interactive elements including movies, sounds, buttons, and hyperlinks.
  • Annotations within the bleed box.
  • Preseparated PDFs.
  • Transfer functions.
  • Actions and JavaScripts.
  • Embedded PostScript®.
  • PDF/X files do not set a minimum image resolution nor limit the plates used.