On January, 11th I have conducted a webinar for the Ghent Workgroup (GWG) on the Ghent PDF Output Suite 5.0 for which I am the project leader in my role as co-chair of the Process Control subcommittee of the Ghent Workgroup.
In preparation of my new seminar PDF Color Management I have tested the image compression before and after color conversion in the most popular PDF tools.
In highend PDFs destinated for quality printing the images are usually compressed using JPEG maximum quality. Before color conversion the images must be decompressed and afterwards compressed again. Acrobat always uses JPEG medium quality for this recompression. The consequence is that there is an (unexpected) loss of quality of the color converted images (see table).
The Ghent Workgroup (GWG) has published an interesting poster:
On the front page the GWG is presented. On the back nine reasons to preflight are listed (compiled by belgian VIGC). Each topic is illustrated with an eample.
This page can be used to check how certain PDF definitions are displayed in different viewers (Acrobat/Reader, Apple Preview, etc.) and output devices (printer, proofer, imagesetter).
In addition one should check this PDF with a preflight tool in order to also detect the problems which are not visible. For this the preflight profiles GWG2012 or GWG2015 (part of Acrobat DC Pro, Callas pdfToolbox, Enfocus PitStop Pro) and of course the preflight profiles for Acrobat Pro from PDFX-ready are highly recommended.
For the new Adobe InDesign export settings V2.5 for PDF/X-4 CMYK+RGB from PDFX-ready the technical committee of PDFX-ready has investigated if a change of the compression method from the traditional JPEG to the newer JPEG2000 would be useful.
JPEG2000 uses a completely different compression technology (wavelet transformation) than the old JPEG (discrete cosine transformation). The new technology promises a better quality together with smaller file sizes. JPEG2000 also allows images with more than 8 bits per channel and up to 256 channels. That sounds promising…
We already knew from tests of the Ghent Workgroup that not all PDF viewers (especially on mobile devices) can handle PDFs with JPEG2000. With other PDF viewers (including Acrobat/Reader) displaying JPEG2000 images is much slower than JPEG images.
But after all we wanted to know if we could recommend JPEG2000 compression for prepress data. That’s why we decided to perform a series of practical tests with a calendar with highres images in different color spaces (Device-CMYK, ICC-CMYK, ICC-RGB). Peter Kleinheider has done the output tests with two different RIPs and I did the export tests with Adobe InDesign CC2017.
When comparing the test results we noticed some unexpected surprises!
There is a problem with PitStop Inspector in Acrobat DC 2017. After starting Acrobat it is impossible to select an object with the PitStop Inspector tool.
This is also true for older versions of Enfocus PitStop. The reason for the problem seam to be a change in Acrobat DC 2017. Enfocus is working with Adobe to find a solution.
The recommended workaround is to open the window Adobe Acrobat DC > About Third-Party Plug-Ins > About Enfocus PitStop Pro… and close it. Afterwards objects can be selected as usual … until the next start of Acrobat DC 2017. Then you have to open the About Enfocus window again!
UPDATE: the problem has been fixed by Adobe in the November 2017 Update of Acrobat.
The biggest problem in PDF workflows for print production is certainly the topic of color. Often there are surprises after printing because the printed colors do not meet the expectations.
PDF/X files have a mandatory output intent but often the color spaces of the objects in PDF/X documents do not match the output intent.
This can be checked very easy with the Color Preflight of the PDFX-ready Online Tools.
Since this happens frequently and the reason is often lack of know how I have decide to create a seminar entitled PDF Color Management (for now only in german). This will be offered at the usual places in Germany, Austria and Switzerland. The first seminar will take place in Olten on 31.8.17.
There are dutch and english translation available at the moment.
In the Ghent version of the guideline only the first part of the PDFX-ready guideline was considered. Unfortunately important topics like PDF preflight and output workflow are missing.
On February 8th at 14:33:51 (CET) the Adobe preflight signature has expired. That’s why it is no longer possible to embed the preflight audit trail after a preflight with Acrobat Pro in a PDF:
After embedding the preflight results the PDF is usually “sealed” with this generic signature. This allows to recognize immediately if the PDF has been altered after the embedding of the preflight audit trail which may make the results obsolete. Thanks to the signature it is even possible to undo these changes.
Unfortunately the Adobe preflight signature is only valid for 5 years. Therefore the signature has to be renewed during the life cycle of an Acrobat version. Last time the signature expired on 22.11.2012. I remember that day very well. At that time I was responsible for the prepress support at Novartis Pharma and I received the error reports from all over the world. Since embedding the preflight audit trail is mandatory for PDFs for packaging files for Novartis Pharma I had to find a solution urgently. I did found out that replacing the invalid preflight signature of Acrobat 9 and X by the newer signature of Acrobat XI solved the problem.
It took Adobe quite a while to do the same. In January 2013 updates of Acrobat 9 and X containing the Acrobat XI signature were released. This signature was valid until 8.2.2016. It was also delivered with the first versions of Acrobat DC.
But this time Adobe has reacted on time (I have pushed them a little bit). With the January update of Acrobat DC and the 11.0.14 update of Acrobat XI a new preflight signature is installed. Users of these applications only have to perform the free update. Afterwards embedding the preflight audit trail is working properly again. At least until 6.11.2020. Then the signature will expire again…
Since Adobe does not offer updates for Acrobat 9 and X anymore, users of these applications must help themselves.
PDF Association has published the PDF/VT Application Notes which have been assembled during serveral month by a working group of the PDF/VT Competence Center chaired by Martin Bailey (CTO of Global Graphics). Some parts of the brochure Do PDF/VT Right by Global Graphics have been integrated.
The 47 page document is targeted to developers as well as users of system for creation and output of variable data and describes the advantage and use cases of the ISO standard PDF/VT (VT stands for variable data and transaction printing). Many tipps for building efficient PDF/VT are listed in order to avoid unnecessary computation during output.
At the launch of Acrobat DC existing installations of Acrobat XI have been removed without notice. This raised a lot of protest in the Internet.
It took quite long until Adobe offered a solution. Since the October update there is now a setting in the installer which allows to choose if existing Acrobat installations are removed or not. By default they are still removed!
For a lot of users this new setting comes too late. For them Adobe has published instructions for the re-installation of Acrobat XI. First Acrobat DC must be uninstalled. Afterwards Acrobat XI is installed. The instructions don’t mention that one has to re-install Acrobat DC afterwards (of course without the option to remove older versions!) in order to use both versions on the same computer.
After the installation of Acrobat DC one must often instruct the web browser how to display PDF documents.
In the Adobe help center there are instructions on how to activate Acrobat or Reader in popular web browsers. The following web browsers are covered: Internet Explorer 8 and later, Microsoft Edge, Mozilla Firefox, Google Chrome and Apple Safari.
The Ghent Workgroup has published a Whitepaper on PDF File Aggreation. This covers e.g. placing PDF ads in layout in Adobe InDesign or QuarkXPress as well as imposition of single PDF pages into complete sheets for printing.
This whitepaper describes common problems in PDF file aggregation and gives recommendations to avoid these problems.
Ten years ago we have founded PDFX-ready in Zurich. Since then almost all important swiss printer associations, system integrators, consultants, training institutes, trade magazines and also some vendors support PDFX-ready as Partners. More than 200 users (printers, prepress service providers, graphic designers, ad agencies, publishers and also print buyers) are already Member of PDFX-ready.
The goal of the association is promoting the use of the PDF/X standards (ISO 15930) with clients, creators and receivers of digital artwork. The use of PDF/X is supported with short instructions (called recipes), color settings, export presets and preflight profiles for offset printing and recently als digital printing. For comprehensive background information on PDF/X workflows the popular PDFX-reade Guideline is available for free.
The Ghent Workgroup’s (GWG) Cross Media Subcommittee has released a white paper with test results and best practices for quality control of tablet publishing solutions covering four popular digital publishing solutions that integrate with Adobe InDesign to generate files suitable for use and viewing on tablets. The GWG evaluated these solutions: Adobe Digital Publishing Suite, TwixlMedia Publisher, Aquafadas and AppStudio, using its Designed for Tablets (DFT) Test Suite.
The PDFX-ready Guideline covers the entire workflow from the creation of images and illustrations, the design of the layout, the correct PDF export, preflight and output of PDF/X files. This guideline concentrates on the PDF/X-4 workflow using CMYK and spot colours.