09 janv. 2019 By Dietrich von Seggern
For readers who aren't much aware of PDF 2.0, it is a consistent further development of the PDF standard, which incorporates numerous practical experiences and meaningful detail improvements - it is NOT a revolution that wants to create something completely new. In more than eight years, ISO has developed a 1,000 page standard as a further development of ISO 32000-1 (PDF 1.7). It contains extensions, clarifications, but also deprecations of PDF functions. Wherever standards are used - which in the printing industry means either PDF/X or the recommendations based on GWG or PDFX-ready - the new functions will only be introduced when new versions of these standards and recommendations have been adopted. The ISO is already working on PDF/X-6, the most important feature of which is that it is based on PDF 2.0. Although, publication is not expected for at least the next 1 year, PDF 2.0 will nevertheless become relevant at an earlier point in time, for example when a PDF with 2.0 functions is to be converted to PDF/X. So what really are the most important updates from the output and print point of view.
An important requirement of an even more flexible basic format for the advancing industrialization is that it should be able to map print products consisting of several individual parts in one file. The individual pages of such a composite file must be able to be provided with corresponding individual accompanying information (metadata). In PDF/VT (Variable Data Printing and Transactional Printing), the so-called DPart metadata was developed for this purpose, which is now also contained in PDF 2.0. This makes it possible, for example, to mark pages of a PDF file for postal code areas, so that the print sequence can be postage-optimized. The "mechanics" now provided in PDF provide pages or page areas with metadata enables applications that go beyond variable data printing, e.g. the insertion of job ticket-like information. For example, printers can get all the information they need in one PDF to produce the color cover pages of a product differently from the monochrome content pages. The previously necessary delivery of two PDFs, which then have to be held together in the workflow, or the carrying of external accompanying information on the various components can be eliminated. In the "full version", the PDF pages can then be automatically routed to the correct machines in the workflow. Fascinating? It sure is.
Output Intents were used for the first time in PDF/X-1 to define the print properties relevant for color reproduction that were intended when the PDF was created which essentially consists of an ICC profile, usually a standard profile, e.g. for standardised offset printing "PSO Coated". Until now, however, it has only been possible to store one output intent object per PDF, which is usually sufficient - except in cases such as the one just described, for example when the PDF is partially produced in one color. PDF 2.0 therefore makes it possible to define output intents at page level. Both page-based output intents and the aforementioned DPart metadata are initially "harmless" for today's workflows, as software that has not been prepared for them will usually ignore them. They can nevertheless become significant if they contain production-critical notes that are then not taken into account. In order to benefit from them, DPart metadata must be read out and used for production control. Page-based output intents must be interpreted by color-converting systems and applied as needed.
Spectral measurement data are already defined in the CxF/X-4 standard (ISO 17972-4) and have been adopted in PDF 2.0. For each spot color used in a PDF, spectral measured values can be inserted for printing on unprinted substrate and for printing on black pre-printed substrate. Users can use this information to better reproduce the spot colors - for example on a 7-color digital printing press with CMYK plus Orange, Green, Violet. In addition, the measured values "overprinted" on black enable an optimized definition and simulation of transparently overlapping spot colors. This new feature can therefore make it possible to combine largely automatic processes with increasing quality requirements, which have so far been the rule rather than the exception, especially in the packaging sector.
Last on the list of important updates is Black Point Compensation (BPC). Users familiar with color management technologies are already familiar with BPC. This involves taking into account the differences between the maximum black of the source and target color spaces during color conversion (standardized in ISO 18619). Up to now, the user has usually actively set this color conversion characteristic in the engines. In PDF 2.0 it is already possible to specify in the PDF whether Black Point Compensation (BPC) should be used or not. This setting is made at object level and therefore does not necessarily apply globally to the entire PDF. Here, too, more control over color processing is required. However, BPC is by no means new; the feature closes one of the few gaps that PDF has with regard to the requirements of print preparation.
Even if some time will pass before the first PDF files with page-based output intents arrive at the printers, the effects on workflows are not insignificant and cannot be reduced to a single PDF 2.0 tool. When purchasing new technology, printers and service providers should therefore make sure that the manufacturer intends to support PDF 2.0, ask for deadlines and even make appropriate agreements if necessary. Finally, I take this opportunity to wish all of you a happy and prosperous new year.