They say a problem shared is a problem halved. Well, two weeks on from our launch of our Advanced Inkjet Screens it’s been gratifying to see how much the discussion of inkjet output quality has resonated among the press vendor community.
Advanced Inkjet Screens are standard in the ScreenPro screening engine
Just in case you missed it, we’ve introduced a set of screens that mitigate the most common artifacts that occur in inkjet printing, particularly in single-pass inkjet but also in scanning heads. Those of you who’ve attended Martin Bailey’s presentations at the InkJet Conference ( The IJC) will know that we’ve been building up to making these screens available for some time. And we’ve worked with a range of industry partners who’ve approached us for help because they’ve struggled to resolve problems with streaking and orange peel effect on their own.
Coalescence on inkjet is directional and leads to visible streaks.
Well, now Advanced Inkjet Screens are available as standard screens that are applied by our ScreenPro screening engine. They can be used in any workflow with any RIP that allows access to unscreened raster data, so that’s any Adobe PDF RIP including Esko. Vendors can replace their existing screening engine with ScreenPro to immediately benefit from improved quality, not to mention the high data rates achievable. We’ve seen huge improvements in labels and packaging workflows. Advanced Inkjet Screens are effective with all the major inkjet printheads and combinations of electronics. They work at any device resolution with any ink technology.
Why does a halftone in software work so well? Halftones create an optical illusion depending on how you place the dots. Streaking or graining on both wettable and non-absorbent substrates can be corrected. Why does this work in software so well? Halftoning controls precisely where you place the dots. It just goes to show that the assumption that everything needs to be fixed in hardware is false. We’ve published a white paper if you’re interested in finding out more.
The Mirror screen mitigates the orange peel effect common when printing onto tin cans, plastics, or flexible packaging
Congratulations to our very own Martin Bailey and to Peter Wyatt, the general manager of CiSRA, for being nominated co-chairs of the PDF Technical Working Group (TWG) within the PDF Competence Centre branch of the PDF Association. https://www.pdfa.org/working-group/pdf-competence-center/
Following the publication of the new ISO PDF 2.0 standard – ISO 32000-2 in July 2017, the PDF TWG will be producing PDF 2.0 Application Notes to support the implementation of the standard by developers whose PDF tools create and consume PDF.
ISO 32000-2 is the first PDF specification developed within the ISO working-group structure involving subject matter experts from many countries and is the first “post Adobe” standard since they handed over its development to the ISO.
Speaking on news of his appointment Martin said, “The value of a standard can be greatly increased by a wider involvement of the relevant communities in shared education and discussion. The PDF Association has become the obvious group to help foster and guide that wider involvement for PDF itself and for many of the PDF-based standards in use today.”
Duff Johnson, the PDF Association’s executive director said, “PDF 2.0 is designed to be largely backward compatible, but older processors won’t handle new features. The purpose of the new documents that will be developed by the PDF TWG is to help developers develop a common understanding of the new specification as well as best practices for implementation.” We’re very happy that Martin and Peter have agreed to lead this effort.
Martin Bailey is the primary UK expert to the ISO committees working on PDF, PDF/X and PDF/VT. In 2017 Global Graphics Software hosted two PDF 2.0 interoperability workshops on behalf of the PDF Association to provide a way for PDF tool developers to validate their work against the new ISO 32000-2 (PDF 2.0) standard by working with vendors of other tools.
In this latest post, Global Graphics CTO Martin Bailey goes back to basics and explores what you need in a RIP to drive a digital press for labels & packaging.
Martin highlights rendering your jobs correctly, color management with CMYK inks and spot colors, PDF layering and technical separations, and provides a high-level view of the features of the Harlequin RIP® for digital labels and packaging.
When you speak frequently at industry events as I do, you can tell what resonates with your audience. So, it was very gratifying to experience the collective nodding of heads at the Inkjet Conference in Neuss, Dusseldorf this week.
I gave an on update mitigating texture artifacts on inkjet presses using halftone screens.
You see, it turns out that there is more commonality between inkjet presses than we previously thought. I’m not saying that there is no need for a custom approach, because there will always be presses with specific characteristics that will need addressing through services like our BreakThrough engineering service.
What I am saying is that we’ve discovered that what matters most is the media. And it gives rise to two distinct types of behavior.
On reasonably absorbent and/or wettable media drops tend to coalesce on the substrate surface in the direction of the substrate, causing visible streaking especially in mid and three-quarter tones. These issues are amenable to correction in a half tone.
Whereas on non-absorbent, poorly wettable media such as flexible plastics or metal, prints are characterized by a mottle effect that looks a bit like orange peel.
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This effect seems to be triggered by ink shrinkage during cure. This can be corrected with a halftone with specially designed characteristics. We have one in test on real presses at the moment.
So it won’t be long now before we introduce two advanced screens for inkjet that will greatly improve quality on the majority of inkjet presses. One to counteract streaking. The other to counteract the orange peel effect. And the next project is to address non-uniformity across the web. Fixing that in software gives you the granularity to address every nozzle separately on any head/ electronics.
And for those presses aforementioned with unique properties that need special tuning? Our Chameleon design tools can create unique halftones for these cases.
Our corporate communications director, Jill Taylor, talks to Roy Faigenbloom of HP Indigo at Labelexpo Europe last month about the new digital front end driving the HP Production Pro for Indigo labels & packaging.
HP Indigo chose the Harlequin RIP as the RIP engine in this new DFE, which has been designed to drive all HP Indigo digital labels and packaging presses and has been rated as 5x faster than the previous DFE.
With Labelexpo Europe 2017 less than a week away, it won’t be long before we start to pack the car and head off on the Eurostar to Brussels.
It’s going to be an exciting show for us this year, with some key announcements from our major OEM customers – we’re looking forward to supporting them and demonstrating our technologies.
If you have to create a digital front end but don’t know where to start, come and talk to us. With Fundamentals, we’ll show you how you can bring your digital inkjet label press to market quickly and easily. Our BreakThrough Technical Services team will also be on hand to answer your questions from color management to screening.
We also have some new features for labels and packaging in the Harlequin RIP® to show you, including controls for deciding when to blend emulated spot colors with process colors for exceptionally accurate brand color matching, and extended controls over PDF layers so that optional content used in process control can be individually switched on or off.
We’ll be on Stand 9B17, so please stop by and say hello. If you’d like to book an appointment, simply contact us: sales@globalgraphics.com. In the meantime, we’ve made this short video to whet your appetite. Enjoy!
Last week was the first PDF 2.0 interop event in Cambridge, UK, hosted by Global Graphics on behalf of the PDF Association. The interop was an opportunity for developers from various companies working on their support for PDF 2.0 to get together and share sample files, and to process them in their own solutions. If a sample file from one vendor isn’t read correctly by a product from another vendor the developers can then figure out why, and fix either the creation tool or the consumer, or even both, depending on the exact reason for that failure.
When we make our own PDF sample files to test the Harlequin RIP there’s always a risk that the developer making the file and the developer writing the code to consume it will make the same assumptions or misread the specification in the same way. That makes testing files created by another vendor invaluable, because it validates all of those assumptions and possible misinterpretations as well.
It’s pretty early in the PDF 2.0 process (the standard itself will probably be published later this month), which means that some vendors are not yet far enough through their own development cycles to get involved yet. But that actually makes this kind of event even more valuable for those who participate because there are no currently shipping products out there that we could just buy and make sample files with. And the last thing that any of us want to do as vendors is to find out about incompatibilities after our products are shipped and in our customers’ hands.
I can tell you that our testing and discussions at the interop in Cambridge were extremely useful in finding a few issues that our internal testing had not identified. We’re busy correcting those, and will be taking updated software to the next interop, in Boston, MA on June 12th and 13th.
If you’re a Harlequin OEM or member of the Harlequin Partner Network you can also get access to our PDF 2.0 preview code to test against your own or other partners’ products; just drop me a line. If you’re using Harlequin in production I’m afraid you’ll have to wait until we release our next major version!
If you’re a software vendor with products that consume or create PDF and you’re already working on your PDF 2.0 support I’d heartily recommend registering for the June interop. I don’t know of any more efficient way to identify defects in your implementation so you can fix them before your customers even see them. Visit https://www.pdfa.org/event/pdf-interoperability-workshop-north-america/ to get started.
And if you’re a PDF software vendor and you’re not working on PDF 2.0 yet … time to start your planning!
About the author
Martin Bailey, consultant at Global Graphics Software, is a former CTO of the company and 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.
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Recently my wife came home from a local sewing shop proudly waving a large piece of material, which turned out to be a “swatch book” for quilting fabrics. She now has it pinned up on the wall of her hobby room.
It made me wonder how many separations or spot colors I’d ever seen in a single job myself … ignoring jobs specifically designed as swatches.
I think my personal experience probably tops out at around 18 colors, which was for a design guide for a fuel company’s forecourts after a major redesign of their branding. It was a bit like a US banknote: lots of colors, but most of them green!
But I do occasionally hear about cases where a print company or converter, especially in packaging, is looking to buy a new digital press. I’m told it’s common for them to impose together all of their most challenging jobs on the grounds that if the new press (or rather, the DFE on the new press) can handle that, then they can be confident that it’ll handle any of the jobs they receive individually. Of course, if you gang together multiple unrelated jobs, each of which uses multiple spot colors, then you can end up with quite a few different ones on the whole sheet.
“Why does this matter?” I hear you ask.
It would be easy to assume that a request for a spot color in the incoming PDF file for a job is very ephemeral; that it’s immediately converted into an appropriate set of process colors to emulate that spot on the press. Several years ago, in the time of PostScript, and for PDF prior to version 1.4, you could do that. But the advent of live transparency in PDF made things a bit harder. If you naïvely transform spots to process builds as soon as you see them, and if the spot colored object is involved in any transparency blending, then you’ll get a result that looks very different to the same job being printed on a press that actually has an ink for that spot color. In other words, prints from your digital press might not match a print from a flexo press, which is definitely not a good place to be!
So in practice, the RIP needs to retain the spot as a spot until all of the transparency blending and composition has been done, and can only merge it into the process separations afterwards. And that goes for all of the spots in the job, however many of them there are.
Although I was a bit dismissive of swatches above, those are also important. Who would want to buy a wide format printer, or a printer for textiles, or even for packaging or labels, if you can’t provide swatches to your customers and to their designers?
All of this really came into focus for me because, until recently, the Harlequin RIP could only manage 250 spots per page. That sounds a lot, but wasn’t enough for some of our customers. In response to their requests we’ve just delivered a new revision to our OEM partners that can handle a little over 8000 spots per page. I’m hoping that will be enough for a while!
If you decide to take that as a challenge, I’d love to see what you print with it!
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.
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. In his next blog post about the changes afoot, Martin Bailey, the primary UK expert to the ISO committee developing PDF 2.0, looks at halftones, an area where the new specification will offer significant benefits for flexo jobs.
Lists of spot functions in halftones PDF allows a PDF file to specify the halftone to be used for screening output in a variety of ways. The simplest is to identify a spot function by name, but that method was constrained in versions of the PDF standard up to PDF 1.7 to use only names that were explicitly listed in the specification itself. This has been a significant limitation in print sectors where custom halftones are common, such as flexography, gravure … and pretty much everywhere apart from offset plate-making!
PDF 2.0 allows the PDF file to specify the halftone dot shape as a list of spot function names, and those names no longer need to be picked from the ones specified in the standard. The renderer should use the first named spot function in the list that it supports. This allows a single file to be created that can be used in a variety of RIPs that support different sets of proprietary halftones and to select the best one available in each RIP for that specific object.
This functionality is expected to be used mainly for high-quality flexo press work, where it’s a key part of the workflow to specify which halftone should be used for each graphical element.
A PDF 1.7 reader will probably either error or completely ignore the screening information embedded in the PDF if a file using the new list form is encountered. In the flexo space that could easily cause problems on-press, so take care that you’ve upgraded your RIPs before you start to try rendering PDF files using this new capability.
Halftone Origin (HTO) Very old versions of PDF (up to PDF 1.3) included a partial definition of an entry named HTP, which was intended to allow the location of the origin or phase of a halftone to be specified. That entry was unfortunately useless because it did not specify the coordinate system to apply and it was removed many years ago.
PDF 2.0 adds a new entry called HTO to achieve the same goal, but this time fully specified. The use case is anywhere where precise specification of the halftone phase is valuable. Examples include pre-imposed sheets for VLF plate-setters, where specifying the halftone phase for each imposed page can reduce the misalignment of halftones that can occur over very long distances, or setting the halftone phase of each of a set of step-and-repeat labels to ensure that the halftone dots are placed in exactly the same position relative to the design in each instance.
A PDF 1.7 reader will simply ignore the new key, so there’s no danger of new files causing problems in an older workflow. On the other hand, those older RIPs will render as they always have, which would be a missed opportunity for the target use cases.
Halftone selection in transparent areas Up to PDF 1.7 there has been a requirement to apply the “default halftone” in all areas where transparency compositing has been applied. This was problematic for those print technologies where different halftones must be used for different object types to achieve maximum quality, e.g. for flexo. Transparency is used in these jobs most commonly for drop shadows, so that’s where you’re most likely to have encountered problems.
PDF 2.0 effectively gives complete freedom to renderers to apply the supplied screening parameters in whatever way they see fit, but two example implementations are provided to encourage similarity between implementations. One of those matches the requirements from PDF 1.7, while the other applies the screen defined for the top-most graphical element in areas where transparency was applied. The second one means that the screening selected for the drop shadow will now be used, matching requirements for the flexo market.
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.