Twenty years of PDF/X

PDF/X

From PostScript to PDF/X: the development of PDF standards and their influence on the printing industry​

What does PDF have to do with graphic arts and the printing industry?​

The 20th anniversary of the first ISO PDF/X standard in early 2021 is a good opportunity to take a closer look at the development of PDF/X. What did the path to today’s PDF/X standard look like, and what influenced the development of other PDF-based standards?

Start of Adobe PostScript in 1984: from PostScript to PDF/X​

The development of PDF/X began with Adobe PostScript in 1984, closely linked to printer development and the changes in the printing industry at that time. The innovative aspect of PostScript was that, in its purest form, it was neither vendor-specific nor device-specific and offered a full set of integrated graphics operators. Graphics and print page files were created in PostScript format so they could be printed reliably and without loss on different output devices.

Although PostScript is considered a page description language, it is also a stack-based, fully interpretive programming language with built-in mathematical functions. As a kind of general-purpose programming language, accounting applications and games, for example, can be written in PostScript.

So, above all, PostScript offered a great deal of flexibility, but it was not without its problems. PostScript was not page-independent, for example, and there were difficulties if you wanted to reprint individual pages or the like. In addition, PostScript was often bound to certain devices in practice.

The 90s: Elaboration and improvement of PostScript​

John Warnock is considered the founder of Adobe, along with Charles Geschke, who died in April 2021. He recognised the strengths of PostScript for publishing and worked on his vision of Interchange PostScript (IPS), removing the high overhead and lack of deterministic behaviour of a general-purpose programming language and adding full page independence. Further developments in this area finally led to the birth of the Portable Document Format (PDF) and the first version of Acrobat in 1993.

At that time, the industry was looking for a viable alternative to PostScript that could be used not only for on-screen graphics but also for print output. The first mature PDF generation (PDF 1.2 / Acrobat 3.0, end of 1996) developed out of this need. In contrast to PostScript, PDF offered several advantages, including page independence and device independence with external print job control. It was also suitable for long-term archiving and later corrections or edits.

PDF/X advantages in terms of functionality, reliability and performance​

As a result, the printing industry also adopted PDF, and the PDF/X standard was developed because the growing size and complexity of the PDF specification posed challenges for print publishing.

All parties involved were looking for a way to "blindly exchange" PDF files for print output. It should be guaranteed at all times that all files could be printed without errors and post-processing at the recipient. So the first PDF/X-1 standard was developed and published in 1999. X here stands for "blind exchange". PDF/X was then further developed as a multi-part ISO standard 15930.

The aim of the various parts of ISO 15930 was to maintain the required degree of flexibility while minimizing uncertainty. Of the two conformance levels of ISO 15930-1:2001, PDF/X-1a became particularly successful due to its relative simplicity and ease of use. This applied to both publishers and print service providers, as PDF/X-1a proved to be a reliable PDF subset that significantly improved publishing workflows.

The PDF/X standards continued to evolve after PDF/X-1a gained strong acceptance and the changes that were also occurring in the world of print needed to be addressed. The need for newer, more advanced PDF/X standards was there.

Further developments after PDF/X-1a​

Adobe PDF 1.4 finally introduced solid support for live object transparency, which was an important demand from the creative industry. Adobe PDF 1.5 added JPEG 2000 image compression and optional content groups (with layer support and other advanced features) as well as object streams and their compression. With the ISO PDF 2.0 specification, official support for black point compensation was then added. You can read more about this in the highly recommended four-part series of articles by the PDF Association, which describes the 20-year development of PDF/X in detail:

The future of printing technology​

Digitalisation may have given the impression that the printing industry will no longer play a major role in the future. But this is a fallacy. Certainly, the nature of printing and the things that are printed have changed massively. The modern way of printing compared to printing 20 years ago is technically much more sophisticated and serves different purposes. Nevertheless, printing technology is still needed and the printing industry continues to evolve.

In the third part of the series of articles about PDF/X on pdfa.org, author Dov Isaacs brings several concrete examples of what today's print jobs look like and what this means for PDF/X:

20 years of PDF/X: important lessons learned​

Victory and defeat are sometimes close together. There have been some important successes within the 20-year history of PDF/X. At the same time, there have been problems in the industry and in the standards development process.

On the one hand, the reliability of the end-to-end publishing process has improved significantly with the use of PDF/X standards, especially when using the most appropriate version of PDF/X for the content and production requirements. For content with colour and/or transparency effects, for example, using a PDF/X-4-based workflow generally produces more reliable and consistent results than a PDF/X-1a-based workflow. It turns out that careful definition and use of well-defined subsets of the PDF specification can greatly optimise many workflows. An example of this is PDF/A for archiving. On the other hand, PDF/X standards have unfortunately been slow to be adopted, ultimately causing the printing industry to suffer.

Many factors can play a role in the slow acceptance of PDF/X-4 or PDF/X-6​

In some cases, the use cases presented by standard developers did not sufficiently reflect real customer needs. In addition, as in many industries, outdated processes are often retained, or documentation and training are lacking. Print service providers and print associations should therefore play an active role in driving broader adoption of new standards.

It is important to bring the two perspectives and experience together. Both technology experts from the industry who develop the standards and the manufacturers or the product managers of the manufacturers should sit at the same table. After all, the most important thing is that the standards are ultimately implemented in products. In addition: the suppliers and printing associations should also be trained in the technical background.

You can find out more about PDF/X sub-formats in Part 2 of the PDF Association series.