pdf/vt – Global Graphics Software blog

February 2, 2023February 23, 2023

Digital watermarking in print workflows – Part 2 – When to add a digital watermark

In this second post about digital watermarking in the print workflow, author Martin Bailey explains the stages when it’s possible to add a digital watermark.

Digital watermarking is an emerging technology, part of the latest step on the evolution of product identification. Global Graphics Software has partnered with Digimarc, a leader in digital watermarking and a member of our Partner Network, to explore this topic and future developments.

Adding a digital watermark during the design stage

In some workflows the designer may apply digital watermarks to a design by, for instance, using a plugin to an application such as Adobe Illustrator. This is equally appropriate for both steganography and an artwork masking layer, and gives the maximum opportunity for approval of the design with the digital watermark in place, and for any rework to the design that might be requested to realize the greatest benefit from using that watermark.
It will not normally be appropriate for the digital watermark to be added by the designer if each instance of the print requires unique data to be encoded in it; variable data composition is usually performed later in the workflow.

Application of digital watermarking has different advantages and disadvantages at various stages in the design and production workflow.

Adding a digital watermark in composition/prepress

In other workflows adding the digital watermark may be a function of a variable data composition or prepress department. Just as for application by the designer, this is applicable for both steganography and an artwork masking layer. There is a reasonable opportunity for approval of the design with the digital watermark in place. But it would be slower and more expensive to rework the design if that is required at this stage than if the watermark were added by the designer.

If the digital watermark is added in prepress then it can carry both static and variable data. As discussed above, however, variable data is best suited to use of an artwork masking layer rather than steganography, if only because of the amount of data that must be generated and then incorporated into a PDF file when steganography is used for a significant number of unique codes.

But applying even an artwork masking layer in prepress does bulk up the resulting print-ready PDF file with many copies of that layer, each one carrying different data. And it can also slow down processing in the Digital Front End (DFE) for a digital press. An overprinted graphic covering large areas of each piece of output in the PDF file can make it harder for the variable data optimization in a DFE to break the design apart so that it can minimize the total amount of processing required to read, color manage, render and halftone screen the job. (See Global Graphics Software’s guide: Full Speed Ahead: How to make variable data PDF files that won’t slow your digital press.)

Late-binding in the Digital Front End (DFE)

A new development in the application of digital watermarking is to add the marks right at the very last minute before the data is printed. In our SmartDFE™, for example, this can be done in parallel with or after the color management and rendering.

Applying the watermarks in parallel with color management and rendering (in the RIP) allows full access to all color channels for the output, while also removing the need to generate a fully resolved “optimized PDF” or PDF/VT file containing all of the variable data further upstream. In turn, this can reduce the overhead of optimizing variable data processing in the RIP. The final result is increased throughput, both in composition/prepress and in the DFE.

Applying marks after the RIP enables even higher performance through the DFE, with the added benefit of providing a more predictable processing speed because the amount of processing required is more deterministic than is rendering PDF. This might restrict the watermark to be painted in only one color channel, though.

Increasing speed and predictability in the DFE allows the use of lower cost hardware in those DFEs, or assists with printing at full engine speed for a larger proportion of jobs.

Late-binding application of digital watermarks will also always occur in an environment where the characteristics of the press that will be used to print the items are known, including resolution, bitdepth etc.

These benefits make this the optimum choice for highly efficient printing workflows for variable data digital watermarks, driving digital presses at full engine speed. The trade-offs are that it’s a little harder to review and approve proofs of the output, and that use for images with steganography is not usually appropriate.

This is an excerpt from the white paper: Optimizing Digital Watermarking in Print Workflows. To learn more about digital watermarking download your copy:

DOWNLOAD YOUR COPY OF THE WHITE PAPER

About the author

Martin Bailey, CTO, Global Graphics Software

Martin Bailey, former distinguished technologist at Global Graphics Software, is currently the primary UK expert to the ISO committees maintaining and developing PDF and PDF/VT. He is the author of Full Speed Ahead: how to make variable data PDF files that won’t slow your digital press, a guide offering advice to anyone with a stake in variable data printing including graphic designers, print buyers, composition developers and users.

Time for an update on VDP!

Over the last fifteen years variable data in digital printing has grown from “the next big thing” with vast, untapped potential to a commonly used process for delivering all manner of personalized information. VDP is used for everything from credit card bills and bank statements to direct mail postcards and personalized catalogues, from college enrolment packs to Christmas cards and photobooks, from labels to tickets, checks to ID cards.

This huge variety of jobs is created and managed by an equally huge variety of software, from specialist composition tools to general purpose design applications carefully configured for VDP. And they are consumed by workflows involving (or even completely within) the Digital Front End (DFE) for a digital production press, where jobs must be imposed, color managed.

Time, then, to update our popular “Do PDF/VT Right” guide which has had thousands of downloads since it was first published in 2014 not to mention the number of printed copies distributed at trade shows and industry events.

Do PDF/VT Right - How to make problem-free PDF files for variable data printing — Do PDF/VT Right – How to make problem-free PDF files for variable data printing

In addition to a general overhaul there is a new section on the new ISO 21812 standard that allows workflow controls to be added to PDF files, and notes on Harlequin-specific hints, to get even more speed out of your DFE if you are a Harlequin user.

The goal remains the same: to provide a set of actionable recommendations that help you ensure that your jobs don’t slow down the print production workflow … without affecting the visual appearance that you’re trying to achieve. As a side benefit, several of the recommendations set out below will also ensure that your PDF files can be delivered more efficiently on the web and to PDF readers on mobile devices in a cross-media publishing environment.

Some of the recommendations made in this guide are things that a graphic designer can apply quickly and easily, using their current tools. Others are intended more for the software companies building composition tools. If all of us work together we can greatly reduce the chance of that “heart-attack” job; the one that absolutely, positively must be in the post today … but that runs really slowly on the press.

Download your copy here .

January 6, 2017November 21, 2019

Getting to know PDF 2.0: not only but also!

In the middle of 2017 ISO 32000-2 will be published, defining PDF 2.0. It’s eight years since there’s been a revision to the standard. We’ve already covered the main changes affecting print in previous blog posts and here Martin Bailey, the primary UK expert to the ISO committee developing PDF 2.0, gives a roundup of a few other changes to expect.

Security
The encryption algorithms included in previous versions of PDF have fallen behind current best practices in security, so PDF adds AES-256-bit and states that all passwords used for AES-256 encryption must be encoded in Unicode.
A PDF 1.7 reader will almost certainly error and refuse to process any PDF files using the new AES-256 encryption.
Note that Adobe’s ExtensionLevel 3 to ISO 32000-1 defines a different AES-256 encryption algorithm, as used in Acrobat 9 (R=5). That implementation is now regarded as dangerously insecure and Adobe has deprecated it completely, to the extent that use of it is forbidden in PDF 2.0.
Deprecation and what this means in PDF!
PDF 2.0 has deprecated a number of implementation details and features that were defined in previous versions. In this context ‘deprecation’ means that tools writing PDF 2.0 are recommended not to include those features in a file; and that tools reading PDF 2.0 files are recommended to ignore those features if they find them.
Global Graphics has taken the deliberate decision not to ignore relevant deprecated items in PDF files that are submitted and happen to be identified as PDF 2.0. This is because it is quite likely that some files will be created using an older version of PDF and using those features. If those files are then pre-processed in some way before submitting to Harlequin (e.g. to impose or trap the files) the pre-processor may well tag them as now being PDF 2.0. It would not be appropriate in such cases to ignore anything in the PDF file simply because it is now tagged as PDF 2.0.
We expect most other PDF readers to take the same course, at least for the next few years.
And the rest…
PDF 2.0 header: It’s only a small thing, but a PDF reader must be prepared to encounter a value of 2.0 in the file header and as the value of the Version key in the Catalog.
PDF 1.7 readers will probably vary significantly in their handling of files marked as PDF 2.0. Some may error, others may warn that a future version of that product is required, while others may simply ignore the version completely.
Harlequin 11 reports “PDF Warning: Unexpected PDF version – 2.0” and then continues to process the job. Obviously that warning will disappear when we ship a new version that fully supports PDF 2.0.
UFT-8 text strings: Previous versions of PDF allowed certain strings in the file to be encoded in PDFDocEncoding or in 16-bit Unicode. PDF 2.0 adds support for UTF-8. Many PDF 1.7 readers may not recognise the UTF-8 string as UTF-8 and will therefore treat it as using PDFDocEncoding, resulting in those strings being treated as what looks like a random sequence of mainly accented characters.
Print scaling: PDF 1.6 added a viewer preferences key that allowed a PDF file to specify the preferred scaling for use when printing it. This was primarily in support of engineering drawings. PDF 2.0 adds the ability to say that the nominated scaling should be enforced.
Document parts: The PDF/VT standard defines a structure of Document parts (common called DPart) that can be used to associate hierarchical metadata with ranges of pages within the document. In PDF/VT the purpose is to enable embedding of data to guide the application of different processing to each page range.
PDF 2.0 has added the Document parts structure into baseline PDF, although no associated semantics or required processing for that data have been defined.
It is anticipated that the new ISO standard on workflow control (ISO 21812, expected to be published around the end of 2017) will make use of the DPart structure, as will the next version of PDF/VT. The specification in PDF 2.0 is largely meaningless until such time as products are written to work with those new standards.

The background
The last few years have been pretty stable for PDF; PDF 1.7 was published in 2006, and the first ISO PDF standard (ISO 32000-1), published in 2008, was very similar to PDF 1.7. In the same way, PDF/X‑4 and PDF/X‑5, the most recent PDF/X standards, were both published in 2010, six years ago.
In the middle of 2017 ISO 32000-2 will be published, defining PDF 2.0. Much of the new work in this version is related to tagging for content re-use and accessibility, but there are also several areas that affect print production. Among them are some changes to the rendering of PDF transparency, ways to include additional data about spot colors and about how color management should be applied.

September 21, 2016November 21, 2019

New task force concentrates on metadata framework

I’m proud to announce that I’m chairing a new task force that has just been created in TC130, the ISO committee focused on standardization for the printing industry. The task force is named “PDF Common Metadata”, and its focus is on constructing a metadata framework that can be embedded within a PDF file to guide production workflow decisions.

We created a precursor to this work in PDF/VT, in cooperation with CIP4. In that case a hierarchical structure of metadata in the PDF file was intended to be used with a templated JDF job ticket (or similar structure) to ensure that complex variable data jobs could be imposed, printed and finished correctly. Unfortunately the model we used set the bar too high and most composition vendors and press manufacturers felt that implementation was too difficult.

But there are a wide range of situations where a simpler model has real value. Indeed, the current work grew out of requests from the transactional print space to be able to include media selections and simplex/duplex controls in a PDF file. That request was initially reviewed by the PDF/VT Competence Center in the PDF Association who concluded that the benefits of a suitable solution would apply across the printing industry, not just in variable data.
The solution proposed is to build on the concept of ‘intents’ from JDF (although not directly on JDF itself). These describe what the final printed piece is supposed to look like, rather than specifying the details of the processes required to make it. The thought process is that the digital front end (DFE) on a digital press can map from that to the actual steps needed.

As a simple example, a request for a specific substrate should be fairly easy to map to an entry in the media library in a DFE and therefore to tray selections (on a sheet-fed press) and to installing the correct ICC color profile. In closed loop workflows such as web to print the first mapping shouldn’t be necessary at all, because the media selection will be pre-populated from the same data as the media library.

The committee met for the first time in San Jose last week, and we’re looking forward to some lively debate. Our first goal is a standard for graphic arts, but there has already been discussion of following on with equivalents targeted more specifically at packaging and at wide format.

If you’re interested in getting involved please contact your national standards body and tell them you want to work in ISO TC130/WG2/TF5. If you don’t know who to contact in your country, drop me a line and I’m happy to make introductions.

March 9, 2016November 21, 2019

Why online print is set to change

Martin Bailey, consultant and former 0CTO, Global Graphics Software

Remember in olden times how you sent a file to print on a wing and a prayer? OK, it wasn’t that bad! But it was unreliable. Figures showed that print-ready file delivery had failure rates of between 30 – 70% and this was a real problem for print service providers with high throughput like magazine houses.

Then PDF/X came along and greatly improved the situation. It was strengthened by additional standardisation efforts from several other bodies including Ghent PDF Workgroup and Altona.

PDF/X worked because it ensured delivery of files ready to high-quality print. And because it dealt with the headache so well, print service providers recommended it.

Fast forward for a moment to today and to the tidal wave that is variable data printing. Most buyers deliver the brief and the dataset to the print service provider (PSP). A full service PSP will offer data mining, graphic design, composition and print. Offering a full service promises higher margins. If you only provide a print service you can expect lower margins, but your model connects better to web-to-print services that are burgeoning. But if you try to “just print” VDP jobs, those that fail will eliminate profit.

I’ve been invited to speak at the Online Print Symposium in Munich (17th – 18th March) about why PDF/VT and Industry 4.0 are set to change online print forever. The truth is that VDP has been hanging around street corners looking for a PDF/X. Well, now it’s found one because that’s what PDF/VT is. It’s been created to deal with every page being different and to give PSPs more control over the workflow.

I would go so far to suggest that print-ready file delivery of graphically rich variable data from outside the print company is unlikely to succeed without it! And on that bombshell…!

To receive a copy of my presentation email me. Meanwhile take a look at http://www.globalgraphics.com/doPDFVTright

February 3, 2016November 21, 2019

PDF/VT – bringing all the advantages of PDF workflow to the world of variable data printing

Standards for variable data printing (VDP) have come a long way since the first work by CGATS to develop a universal delivery format in the late 1990s. In 2010 the International Standards Organization published the PDF/VT standard, marking the first really effective specification for a reliable, vendor-neutral exchange of variable data jobs, both within and between companies.

A special type of the PDF file format, PDF/VT is specifically used for variable data and transactional printing in a variety of environments, from desktop printing to high volume digital production presses. Built on PDF/X, it therefore brings all the advantages of that standard in enforcing best practices for reproducible and predictable color and appearance to the variable data and transactional print worlds.

The industry is gradually realizing its value to improve quality, competitiveness and productivity, and I’ve been working with the PDF/VT Competence Center, especially with Christoph Oeters (Sofha), Paul Jones (Teclyn bv) and Tim Donahue (technical consultant) to produce a new set of Application Notes highlighting the benefits of using PDF/VT and the workflows that it enables.

The Application Notes explain how to make the highest quality and most efficient PDF/VT files to achieve the required visual appearance of a job, so if you develop software to read and write PDF/VT files, for example in composition tools, RIPs, digital front ends and imposition tools, or if you work on print workflow integration, you’ll find the notes really beneficial. They also show how document part metadata can be applied and leveraged for VDP specific production workflows.

Of course, there are wider benefits to using PDF/VT: The adoption of PDF/VT will allow the industry to finally move towards a reliable, vendor-neutral exchange of variable data jobs, simplifying the process of variable data printing significantly.

The application notes are free to download, pick up your copy here: http://www.pdfa.org/publication/pdfvt-application-notes/.

Let me know what you think of them – feedback is always welcome.

Additional reading:

Do PDF/VT right by Global Graphics Software

PDF/VT for personalized print by the PDF/A Competence Center

Read the press release from the PDF Association (http://www.pdfa.org/2016/01/pdf-association-publishes-pdfvt-application-notes-showcasing-the-benefits-for-variable-data-print-streams/)

October 20, 2014November 21, 2019

Free webinars on “Do PDF/VT Right”

For those who missed it at PODi and XPlor, I’m presenting two free webinars this week on “Do PDF/VT Right: how to make problem free files for variable data printing”, hosted by Dscoop University – the Digital Solutions Cooperative. You don’t have to be a member of Dscoop, nor an HP Indigo user to join.

If you’d like to sign up to hear me talk through the guide, download the “Top 5 tips” poster, and have the chance to ask any questions, please register using the following links:

EMEA: Tuesday, October 21, 1pm – 2pm CET: http://dscoop.org/p/cm/ld/fid=971

North America: Thursday, October 23, 11:00 a.m – 12:00 p.m. CST: http://dscoop.org/p/cm/ld/fid=967

The guide itself is, of course, still available at http://www.globalgraphics.com/doPDFVTright/

#dopdfvtright

Tag: pdf/vt