20 years of PDF/X – From PDF/X-1a to PDF/X-6
Today’s current standard PDF/X-6 was developed to meet the future complex PDF print publishing workflows from content creation to rendering and finishing as well as current workflows.
In the meantime, the first ISO PDF/X standard is already 20 years old. In this second part, we will discuss the various sub-formats of PDF/X that have been developed over the years. You can find the first part of our series of articles on PDF/X here…
Further developments based on PDF/X-1a
Since 2001, new versions of PDF/X have been gradually developed. After PDF/X-1a, PDF/X-4:2008 (ISO 15930-7:2008) and its update PDF/X-4:2010 (ISO 15930-7:2010) deserve special mention. It is currently the most suitable PDF/X for content with transparency effects.
What are the advantages and special features of the individual versions?
In 20 years, several variants have been developed with different adaptations. The standards are identified by a year and for each variant there is an individual version of the ISO standard.
- The beginning is ISO 15930-1: PDF/X-1a:2001 – This format is limited to CMYK and spot colours on the basis of PDF 1.3.
- ISO 15930-3: PDF/X-3:2002 – This is an extension on the basis of PDF 1.3 the colour calibrated data exchange beside CMYK and spot colours to further colour spaces like RGB and Lab. Support for ICC colour management for objects within the PDF file has been added, not only for the Output Intent. This PDF/X version, which supports full blind exchange, is supported by major graphics applications and RIPs and has found limited acceptance in Europe. However, acceptance in other countries (especially North America) has been very low.
- ISO 15930-4: PDF/X-1a:2003 updates the 2001 version of PDF/X-1a on the basis of PDF 1.4. Most importantly, CMYK and spot colours in any combination are supported. PDF 1.4 added robust support for live object transparency (including transparency groups and blending modes). Adobe PDF 1.5 added support for JPEG 2000 image compression, as well as optional content groups and object streams and their compression.
- PDF/X-4: PDF/X-4:2008 (ISO 15930-7:2008) and its update PDF/X-4:2010 (ISO 15930-7:2010) are based on PDF 1.6 and include the colour support of PDF/X-3 and additional features of PDF 1.6, including limited layer support (optional content groups) as well as compressed object streams and some JPEG 2000 image compression support. It is currently the most suitable PDF/X for content with transparency effects.
- PDF/X-5: PDF/X-5 (i.e. PDF/X-5:2008 (ISO 15930-8:2008) and PDF/X-5:2010 (ISO 15930-8:2010) were developed based on Adobe PDF 1.6 as a special version of PDF/X-4. At this time, no major graphics applications are known to support any of the PDF/X-5 conformance levels.
- PDF/X-6: With this version PDF/X-6:2020 (ISO 15930-9:2020) PDF/X-4 was extended by various PDF 2.0 functions. The PDF/X-6 conformance level enables a complete blind exchange.
What about PDF/X-2?
It is noticeable that a PDF-X standard is never mentioned. This is because PDF/X-2:2003 (ISO 15930-5:2003) was withdrawn not long after its publication. There are no known applications that support PDF/X-2.
Since 2020: With PDF 2.0, there was also a new standard for PDF/X: PDF/X-6
Based on ISO 32000-2:2020 PDF 2.0, PDF/X-6:2020 (ISO 15930-9:2020) extends the graphics support of PDF/X-4 to include a wide range of PDF 2.0 features, including but not limited to support for black point compensation, output intents per page (with optional CxF/X-4 spectral data) and document part metadata. The use of annotations within the visible area of a page, as well as non-XFA forms, digital signatures and some actions are now allowed with some notable restrictions:
The PDF/X-6 conformance level allows full blind exchange. Carefully created PDF/X-6 files with some restrictions can be simultaneously marked as conforming PDF/A-4 files for archiving. The PDF/X-6 and PDF/A-4 standards were developed at the same time and care was taken in the development of the standards to ensure this commonality.
As yet, there are no known major graphics applications that support any of the PDF/X-6 conformance levels. And it will be some time before support for PDF/X-6 creation is available in the major graphics applications. Until then, it is recommended to continue using the PDF/X-4 standard.
Today’s print jobs and requirements
Today’s print jobs are increasingly packaging, signage (including large posters and vehicle wraps), artwork, textiles, wall coverings, personalised marketing campaigns, etc. The content of today’s print jobs is typically much more complex than the content of 20 years ago. Thanks to digital photography and more powerful design tools, colour and sophisticated transparency effects are becoming increasingly important for print. This includes colours outside the typical CMYK colour gamut.
Increasingly, the concept of a ‘print job’ goes far beyond one or more pages in one format printed on just one substrate (or paper type) on one press. For example, a book may contain a cover, monochrome text pages on matte paper, fold-in pages and colour pages on thicker, glossy paper. A similar example is variable data printing, where multiple pages, cards, envelopes, etc. are produced as part of a personalised mailer. These different page types may require pages to be ‘pulled’ from different trays or even printed in parallel on multiple devices to be joined together afterwards.
Printers no longer have the luxury of adapting a PDF file so that the content only renders correctly on a single type of device in a particular location. And these devices are much less likely to be CtP (computer-to-plate) devices that support offset printing; digital printing is an increasingly large target for print jobs, especially short-run and/or variable-data jobs. If only for operational purposes, ICC colour management is no longer optional or a feature. Certain functions should be supported as a matter of urgency, including ICC colour management and some functions such as annotations under certain conditions (such as comments, marks, forms, etc.). Thus, the PDF/X standards have also been revised and adapted again and again.
More on the adaptations of the individual sub-formats in the detailed series of articles at pdfa.org: