PDF gets a unifying update

Three cool things you want to know about PDF 2.0

When Adobe’s Portable Document Format (PDF) burst onto the scene in the summer of 1993 it was the Adobe response to a gap in the market: it was very hard to share files across MAC, Windows and Unix environments. From its launch in June of 1993 through the last 25 years of updates, PDF evolved from a simple display format to a comprehensive platform for printing, viewing, archiving, and file sharing. 

By 2008 Adobe had released PDF to the care of the International Organization for Standardization (ISO), which codified it as ISO 32000-1. While there have been updates over the last decade, it wasn’t until July, 2017 that PDF 2.0 was released, responding again to gaps.

For many printers the introduction of PDF 2.0 will have little impact on the day-to-day work. It will take some time for DFE and RIP vendors to catch up to the feature extensions, and on the emitter side it may take time for design products to catch up. While many of the features of PDF 2.0 existed in the wide array of PDF standards, from PDF X-1 to PDF-UA, PDF 2.0 unifies the standard. 

To prepare for the options opened by PDF 2.0, let’s look at the following three areas. 

File Preparation

Many print projects call for producing books, magazines, manuals and marketing collateral using different paper stocks and even different print devices, leaving production teams trying to balance colour without the aid of ICC profiles built for the output environment. In PDF 2.0 this gets easier with support for page-level output profiles. They add a new layer of granularity to how you associate colour profiles. Now you can assign specific profiles to allow for different paper stocks and different presses. This is a huge help to companies running offset, inkjet and toner devices, and mixing pages to create hybrid final products. Similarly, PDF 2.0 now allows for the output intent of an International Color Consortium (ICC) profile to be kept separately from the PDF data structures, which means that the ICC profile can be referenced using a URL. 

If you print graphic work that uses large black areas or features shadows, you will want to investigate the changes to object-level Black Point Compensation (BPC). PDF 2.0 expands BPC control when converting from larger to smaller colour spaces. Designers may remember when BPC control was added to Adobe Photoshop at release 5 to create adjustments between the output device capabilities and the black in the file. An ICC whitepaper called Black-point compensation: theory and application (http://www.color.org/WP40-Black_Point_Compensation_2010-07-27.pdf) describes how using this technique can render more detail in shadows. For prepress teams it is important to remember that Black Point Compensation does not apply to the absolute colourimetric rendering intent, where the goal is the exact reproduction of all colours within the gamut of the output device. 

There is some great news for printers who specialize in packaging, industrial printing or textile printing. PDF 2.0 unlocks the option to use spectrally defined colour to provide an accurate way to emulate spot colours both for proofing and for final print production. Using spectral values is common in packaging printing where the order in which the inks are printed, the dot gain, and screening may vary based on the substrates. 

Using the new feature requires that spectral data be added to a document’s output intent dictionary, using the new entry called SpectralData. The spot colour characterization data is supplied using the CxF/X-4 XML format using the guidelines in ISO 17972-4:2015 (https://www.iso.org/standard/61503.html). 

If you aren’t familiar with spectral characterization of spot colours, it uses measured spectral reflectance values and information on ink opacity. You can learn more about the power of this feature and see some examples on how it benefits your printing on the International Color Consortium website (https://www.iso.org/standard/61503.html). Spectral data for spot colours is already supported by some vendors.

PDF 2.0 includes many changes that impact how transparency is handled. The intent is to get more reliable colour when imposing multiple PDF files from different sources together, as is common when adding display advertising to magazines or building catalogue pages. The caveat is that if you do a lot of this type of work you may notice that your output results vary in a PDF 2.0 environment. 

In an environment where the RIP is at the PDF 2.0 level, it may automatically apply a CIE-based colour space when a device colour space is used in a transparent object. In fact, as PDF 2.0 implementations roll out, you may notice a variety of subtle changes in your output due to alterations to rendering in the specification. The best recommendation is to download the example files from the PDF Association (www.pdfa.org) and build a regression testing suite so that you can identify how your current and future PDF environments behave.

Another caveat for PDF 2.0 covers halftoning and screening. Even though these functions have been considered stable in PDF, the new specification extends options to create a single PDF file that can select the best halftone for a specific object when multiple halftone screens are available. There is also new support for screening transparent objects. These features may be most useful to printers who specialize in high-quality flexo printing where halftone specification for an object is a common part of the workflow. 

For those printers who specialize in engineering drawings and maps, you may have files tagged to use a viewer preference key that specify what scaling to use for printing. In PDF 2.0 there is one additional feature that allows for the scaling factor to be enforced.

When it comes to file preparation, these are just some of the features intended to make print production more consistent. As with any step change in file formats, printers should be testing as they update to ensure that there are no colour shifts or changes in screening to be re-managed. 

Security

Document-level security is a requirement that PDF 2.0 embraces with gusto. It requires stronger encryption and has been enhanced to allow Unicode non-Roman characters for passwords. 

Organizations that use the security features of PDF will have noticed that keeping up with the current best practices has been a struggle. This all changes with PDF 2.0, which now requires the new 256-bit Advanced Encryption (AES 256) and requires that passwords used for encryption must be in Unicode. All other algorithms supported in earlier PDF and Acrobat versions are declared as deprecated, including DES, Triple-DES, AES-128 and AES-192. If you have been using the older AES-256 encryption compatible with Acrobat 9, start to make plans for change. Only the new encryption is supported in PDF 2.0. 

One thing to remember about password protection is that even in PDF 2.0, if the file has an owner password but a blank user password, the file is not protected. If you are exchanging files with clients, come to an agreement with them about the level of security they are expecting and ensure that you have procedures in place to enforce those security levels. 

Accessibility

For many printers, the issue of accessibility is outside the scope of their environments, but as more direct mailers work to ensure that their product can reach not only those with perfect eyesight but also those with sight impairments, the conversation is changing. Many companies already offer solutions that use alternative text to tell assistive technologies what images are in a document, and there are solutions that can translate PDF files into Braille or voice. PDF 2.0 takes the next step by extending the tagging architecture and enabling pronunciation dictionaries. This feature is based on an XML-based W3C format called the Pronunciation Lexicon Specification (http://www.w3.org/TR/pronunciation-lexicon/ ).

If you are serving communities that require accessible documents, take the time to review the PDF 2.0 specifications for what they bring, but also remember to stay up-to-date with changes in regulations. The Web Content Accessibility Guidelines (WCAG 2.0) on the W3C site (https://www.w3.org/TR/WCAG-TECHS/pdf.html) are a great place to learn about the requirements and changes in the world of accessible PDF.

What else is new?

For PDF 2.0 there are many major and minor changes beyond the major rewrite for consistency and clarity. Because PDF 2.0 is, in many ways, a roll-up of the wide array of PDF variations (PDF/A, PDF/US, PDF/X and all of the varieties), the update process could have an impact on the look of the files your produce. You will want to establish a good regression-testing program to ensure that you can make needed adjustments to maintain the look of the work you do for regular clients. 

The update includes rewrites of chapters covering rendering and transparency, which may alter how your print files render. If you are taking advantage of the tagging capabilities in PDF, there are rewrites to the metadata and tagged PDF sections. 

If you are one of the many print shops looking at adding 3D printers to support client requests, PDF 2.0 supports the Product Representations Compact (PRC) 3D file format, which allows for 3D data to be embedded in PDF files. It also enables tools for viewing, measuring and annotating media content. 

One other notable change is something that goes away in PDF 2.0. If you have been using the Open Prepress Interface (OPI) in your homegrown prepress processes, this function has been declared deprecated and removed. Many third-party vendor products have workarounds, but if you are one of the many print shops that wrote your own scripts and protocols, this could require some changes in how you manage low-resolution placeholders. 

Taking advantage of this new feature requires PDF generation tools that support that tagging of the profiles to the pages, and digital front ends and RIPs that support PDF 2.0. This is a great time to talk to your software vendors and your clients to understand their PDF 2.0 plans. 

If you are one of those printers who loves to dig into the technical specifications, this time it comes with a price. The copyright on the PDF 2.0 specification is held by ISO, so you have to buy your copy from their website, www.iso.org.

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