Originally appeared in On Demand Journal
By Chuck Gehman
March 2005
“Any sufficiently advanced technology is indistinguishable from magic” – Arthur C. Clarke, ca. 1961
PDF was first introduced in the late summer of 1992, which (at least to me) now seems like an incredibly long time ago. With the recent launch of Acrobat 7, the excitement for many in the printing industry around PDF has been reinvigorated. In many ways, it’s an even more important development than when Acrobat was first announced. It’s gotten to the point where people widely anticipate any new version of this essential application, and the new capabilities and productivity enhancements it will bring. This article isn’t about Acrobat 7, though. Instead, it offers a good opportunity to talk about the challenges and opportunities PDF offers for commercial print applications, on-demand and VDP.
Certainly, PDF and Acrobat have achieved widespread adoption in the corporate enterprise. This is the engine driving Adobe’s exceptional performance as a tech company. Similarly, the Acrobat product line and PDF as a file format have achieved critical mass in web publishing , among creative staffers at ad agencies, graphic designers, publishers, and developers. A small but important segment of the printing industry has also fully embraced PDF: the early adopters and technologically sophisticated shops, both large and small that have adopted PDF either as an internal format or on a limited basis as a format used by customers to deliver jobs.
PDF Workflow: The Deep Background
The introduction of Adobe Extreme in the fall of 1996 marked the introduction of the idea of “PDF workflow.” In a PDF workflow, PostScript files are interpreted or normalized and converted to individual PDF pages. The PDF pages are then individually processed (e.g. trapped, color corrected, imposed, and rasterized), and multiple pages can be processed simultaneously.
In a PDF workflow, data is maintained as a device-independent digital master. Device-dependent changes are delayed until later in the print production process. The workflow is page-based, which means that if there is a last-minute change in a document, only the changed page requires re-processing.
In contrast, in “legacy” raster-based workflows, PostScript files are converted to rasterized pages at their entry into the workflow. Proponents of legacy raster workflows think that this provides some kind of advantage, in that the “customer” data is locked in early in the process, preventing the introduction of problems with fonts, color fidelity and other details when the further steps of the workflow are performed.
In truth, PDF has significant advantages over working with raster data in the workflow. Like PostScript, it is a specification developed by Adobe, but is made public to encourage third-party development. The principal advantages of PDF include:
- The ubiquitous support of third-party developers
- Smaller file sizes (because the format includes compression)
- Object-oriented: where PostScript is a “stream” that basically references all of the pages in the job at once, PDF permits addressing (or imaging) individual pages. Furthermore, this object orientation allows “programmatic” access to perform operations on elements of a page, on pages themselves, or on collections of pages
- Cross-platform: PDF files work on any system, regardless of the platform on which they originated. They can include embedded fonts and images.
What Are the Challenges?
At this point, one might say, “sounds great, sign me up.” And many have embraced PDF workflow, especially over the last few years. However, there are still significant challenges with using PDF.
Getting Good Customer Files
Although PDF workflow solutions can be used with any type of input file format, substantial labor savings are gained by getting customers to deliver in PDF files, eliminating the need for prepress operators to “convert” native application files (i.e., QuarkXpress, Microsoft Publisher or other formats) into PDF. However, getting customers to create these PDF files without problems (for example, missing fonts and images or incorrect resolution settings), and without requiring operator intervention, continues to be a challenge.
EFI now offers a solution for this problem. EFI’s PrintMessenger PDF generating drivers PrintMessenger allows users to “file-print” from within their favorite applications, delivering settings-correct PDF files to the print service provider via the Internet (the printing company controls the settings in a configuration file that is invisible to the user). This creates a seamless workflow from the user’s desktop computer to the print production environment with one PDF.
Other vendors have created solutions that operate similarly, while still others (perhaps most notable Enfocus with their PitStop application) have created solutions for identifying and correcting problems with PDF files after they have arrived at the shop, before they enter the workflow for output.
Can the PDF be Output (i.e., “printed”)?
Another potential challenge with PDF workflow is the ability for RIPs (Raster Image Processors), the “brains” that drive output devices like CTP machines or digital printers, to keep up with the rapidly changing PDF specification—from a compatibility standpoint. If you are using the latest Adobe applications like Acrobat or InDesign--even if your RIP is up to date with the manufacturer’s latest software release-- you may encounter problems processing customer files. Some things customers can create in PDF documents may require the printer to do considerable work to image the beautiful artwork or pages, basically “down-versioning,” or “re-engineering” work to be compatible with a particular workflow or RIP. Fortunately, some vendors (like EFI) provide the ability to “live update” the RIP software, to make it easier to stay current on the latest release of the RIP software.
Guaranteed Accuracy
One of the biggest issues with PDF continues to be “trust.” As briefly noted previously, “legacy” raster formats were once embraced by creatives, publishers and print service providers alike because they provided the closest thing to a “guarantee” possible in the digital world that the file received and output by the printer was what was delivered by the customer. The idea is “digital film,” because color-separated film is the medium that agencies and magazine publishers had traditionally used to exchange materials.
Early attempts to switch to “digital film” for transmitting and processing job materials (most notably advertising) involved a legacy raster file format called TIFF/IT-P1, which had a number of limitations, such as extremely large file size and inability to automate processes by nature of its raster format. The answer to many users became a newer format, a variant of PDF, called PDF/X, which is rapidly replacing TIFF/IT-P1, and is now an ISO (International Standards Organization) standard.
PDF/X extends the use of PDF to file exchange (hence the X). The primary goal is to assure PDF file creators that the fidelity of their content will be maintained at the destination. A standard of this kind has many advantages for making job delivery reliable and robust. Because it is an open specification that any vendor can implement without license fees, it can be used with virtually any tool for making or preflighting PDF files.
Because it is a subset of the PDF specification, PDF/X-1a creates files that can be opened and displayed in any PDF viewer. This by itself is a huge advantage over the TIFF-IT/P1 format. What’s more, any PDF production workflow can also process PDF/X-1a files. However, since an important benefit of PDF/X-1a is that it ensures a file will be rendered in the same way by every system, using a non-compliant workflow could compromise the integrity of the file. In this circumstance, the output might not match the original.
PDF and VDP
As noted, two of the biggest advantages of PDF are its object oriented nature, which allows operations to be performed on page elements, pages and jobs “programmatically,” i.e., from software rather than by labor intensive manual processes, and second, the interoperability provided by nature of its open format and broad third-party software developer support.
Nowhere are these advantages more important in print than in the world of VDP (Variable Data Printing), where we are working with potentially tens of thousands of unique pages in a single job.
PPML, an output specification created by the members of the Print On Demand initiative (PODi), is an open, XML-based language for variable data printing. It provides an optimized print option that is intended to create a universal output standard, which also is designed to result in a faster RIP time. The advantage of emitting and consuming PPML is inter-operability, like PDF itself. With a shared output language, software and hardware developers alike should have a broader market and customers have more flexibility when creating a file for print. EFI’s Fiery color servers support PPML and are optimized for printing variable information at rated engine speed.
PDF and JDF
PDF contains the job content, but doesn’t explain to a printing company how to produce a job. That’s where JDF can help in a PDF world. Much effort is currently being put forth by leading vendors like Adobe and EFI on the “intent” side of the JDF specification. The goal is that when a job is created in an application like InDesign, a user can fill out a simple job ticket, send the file over the Internet to the print shop (using a tool like EFI’s aforementioned PrintMessenger and EFI PrinterSite Exchange) and have the operator at the shop know exactly what to do with it-- because the ticket contains the embedded job information. And that this would happen, presumably:
- Without opening job files and poking around to determine “what is in it”
- Without multiple telephone conversations to get to the root of what the creator wants
- Without having to “fix” problems manually, that might be caused by missing graphical elements, or mistakes in application or Acrobat settings
For some jobs, it will even be possible-- with the combination of PDF and JDF-- for the job to flow directly into an output queue, and not be touched once by human (i.e., prepress operator) hands.
Acrobat 7 and Commercial Print
Adobe has been exhibiting renewed interest in the professional printing applications market of late. It seems likely that the success of InDesign has contributed to Adobe’s renewed emphasis. As I mentioned at the beginning of this piece, Acrobat 7 is quite a leap forward for professional print. Among the great new features in the application include:
- It’s much faster loading, reason enough to upgrade from Acrobat 6.
- Prepress users will enjoy new preflight capabilities: correct inks, adjust color spaces and fix line weight problems, and more. Users can also flatten live transparencies, convert color spaces and create trap presets for PostScript printing.
- Microsoft Publisher support: MS Publisher has been a bane to commercial printers, for various reasons, especially users’ lack of knowledge of commercial print processes. Now, users can create “better” PDF files right from within the application.
- Microsoft Outlook support: Acrobat now provides integration with Outlook for organizing and publishing information in emails.
- Better security: it’s easier to configure document-level security settings.
- PDF Organizer: new search and history features help users find files more easily in the sea of documents on a hard drive or network.
PDF in the Future
PDF is not yet the solution to all of the industry’s challenges, but it certainly one of the most important weapons in the battle for interoperability, streamlined business and production process, and enhanced profitability. Better quality input files, better information about job intent, automation and seamless integration with output devices all make PDF an essential tool for printing operations, regardless of printing technology or size of company. Don’t wait for Acrobat 8 or PDF 2.0 to begin to reap the advantages of PDF in your workflow— you can start today!
