PDF Association logo.

Facebook
Twitter
YOUTUBE
LINKEDIN
XING
About the contributor
Dietrich von Seggern

After receiving his degree as printing engineer, Dietrich von Seggeern is in 1991 starting his professional career in the area of processing of digital print data. He is involved in several research projects around data transmission in publishing using at that time new broadband networks. In this context he is also working on standardization of digital data formats and in 1997 he encounters for the first time the PDF format for these purposes. Since 2002 he is working for callas software in several leading professions. One of his main focusses is the international standard for PDF in digital archives: PDF/A. callas software was involved in the standardization process at ISO before the first part is published in 2005; further standard parts, PDF/A-2 and PDF/A-3 follow.
More contributions
Save-The-Date: PDF Day France, Toulouse, April 4, 2019

PDF Day France will be the first French-speaking event of the PDF Association, organised by our member ORPALIS. It will take place in Toulouse which is the home ground of Airbus and we are very happy that Airbus will present a case study around its usage of PDF in their document management environment!

Electronic Document Conference: Call for Papers

Prospective presenters at the Electronic Document Conference 2019 are invited to submit high-quality original proposals for 25-minute presentations on subjects of interest to developers and technical product managers concerned with electronic document implementations.

Have we passed ‘peak PDF’?

How do we gain insight into how users’ views of documents are shifting? Google Trends is an increasingly interesting source of high-level marketplace data. By aggregating Google’s search data over time, reporting a term’s popularity as compared with all other searches.

Participating in the PDF Techniques Accessibility Summit

The PDF Techniques Accessibility Summit’s objective is to establish a broad-based understanding of how PDF files should be tagged for accessibilty. It’s an opportunity to focus on establishing a common set of examples of accessible PDF content, and identify best-practice when tagging difficult cases.

Members supporting PDF features!

The typical adoption curve for PDF technologies until approximately 2007 tended to track with that of the original PDF developer. Since then the marketplace has shifted; it’s no longer clear that Adobe drivesPDF feature support worldwide. Accordingly, we are happy to report that adoption of PDF 2.0 continues apace, with new vendors announcing their support every month.

PDF/A and PDF/X at the Same Time

In an increasing number of inquiries that we are receiving not only one PDF-based ISO standard is required. In many cases compliance with PDF/A and PDF/X should be achieved. But always one of these standards is more important in the respective environment: An organization may want to generate print output which at the same time should be archived, or a print shop may want provide archive ready files to its customers. In both cases PDF/X compliant files should be created which at the same time comply with the PDF/A standard. Or in an archival project it may be important that the archival PDFs do comply also with PDF/X in order to make sure that they can be output on a high end printing device – today or in the future. In many such projects questions arise about what are the differences between the two PDF based ISO standards and the following brief overview should shed some light on this. (Whoever is interested in more details may just want to try our pdfaPilot solution that has predefined profiles for converting into more than just one standard.)

First of all from a high level perspective there are not many differences in the two standards. This is actually no surprise because some “design goals” for both standards are the same: Reliability, paper like appearance and completeness.

On a more detailed level both standards require that all fonts need to be embedded and prohibit the presence of dynamic actions or java script.

The most important difference is that PDF/A allows for comments and forms which is not the case in PDF/X. That makes sense because these objects are usually not printed. But in workflows that should support both standards this may be the only real problem. The only way to convert both into PDF/X would be to flatten them into the page content, which would actually mean that they cannot be used as annotations or form fields anymore.

Everything that is by nature not visible on the page like structure information or unicode which are covered by the PDF/A conformance level “a” does simply not have the same importance in PDF/X as in PDF/A. However, there is no rule that would say that both may not be used in a PDF/X file.

Metadata plays a major role in PDF/A because it helps to understand the purpose of a PDF or to retrieve it from the archive. In PDF/X only in the newest part of the standard, PDF/X-4, there are rules for XMP Metadata. The requirements are similar to PDF/A.

An other important difference between both standards is in the field of color. That is due to the fact that many print workflows are based on the print color space, CMYK, while in PDF/A nearly always the standard monitor color space sRGB is used. As said before there are three different parts of PDF/X that are practically used: PDF/X-1a, PDF/X-3 and PDF/X-4. In the newer flavors, PDF/X-3 and PDF/X-4, both color spaces, CMYK and/or sRGB may be used. One of the most important decisions that has to be made in such projects is in which way color spaces should be converted in order to meet the requirements in the respective project in the best possible way. Both standards are flexible enough to cover concrete requirements, it may just be required to adjust the conversion settings accordingly.

In general PDF/A and PDF/X are technically close and in most cases it should be easy to convert a PDF file into one that complies with both standards at the same time. The only important exception to that rule are PDF files with annotations or form fields. Practically it will be required to make a decision on the color space approach which will be based on whether it is more a PDF/A or a PDF/X project.


Tags: color spaces, conversion, pdfaPilot, printing, publishing
Categories: Architecture, Engineering & Construction (AEC), Forms, PDF/A, PDF/X, Print & Publishing, XMP