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Jun 1, 1999 12:00 AM
Considering the amount of attention PDF is currently receiving, it would seem unlikely that we need another article about its virtues. However, even with all of the discussion, there is still a lot of confusion about PDF's status and what role the technology plays in today's graphic arts industry.
If we look at PDF's most visible role, it is as the chosen format in the Associated Press AdSend program. This program supports the digital delivery of advertising to more than 1,600 daily, weekly and monthly newspapers. And it's not just being used for black-and-white ads--it is also used for color advertising. Because of PDF's small file size, it is ideal for applications involving the many telecommunication options that exist today. PDF can ensure quick, compatible digital ad transmissions almost anywhere around the globe. So if PDF files can be used to supply advertising to newspapers globally, why isn't it more widely used in other forms of publishing production? In order to fully appreciate the issues, we need to understand what makes PDF so valuable--and what obstacles can deter its widespread adoption.
There are a number of features that make PDF valuable for different uses. Some of those features include device independence, page independence and cross-platform support with a free, readily available reader. Device and page independence are key factors as we look at the changing roles of publishing and output processes--and the need to display or output the same file to multiple devices in an increasingly automated production environment.
While PostScript has been the format of record for many of these tasks to date, it is very dependent upon specific setups for each device. PostScript neither supports page independence nor the ability to view or extract a single page from the complete file.
PDF files also are complete when prepared correctly, including all font and image information. In addition, this same file can be viewed on multiple platforms, including Macintosh, Windows and Unix. This makes PDF an ideal format for soft proofing content and perhaps even color (if you have implemented good color management protocols).
As design creation applications, native PDF files are not quite ready for prime time--yet. While some applications, such as Adobe PageMaker, Illustrator and Photoshop, allow users to save or export files as PDF, this isn't what production people think of as native application files. Today, there isn't an application that allows users to work with a PDF layout in its entirety.
The recently announced design and layout application software, Adobe InDesign, reportedly handles native PDF layout application files that can be used to go directly to print.
Currently, the best way to make a print-ready PDF file is to use Adobe Distiller, an application that processes PostScript into a PDF file. The question remains, however, are those native PDF application files necessary if we can create a PDF file from almost any application using Distiller. The answer depends on your position in the publishing process. If you are a designer, it might be nice to have PDF as a consistent format across all of the major Adobe design packages, including InDesign, Illustrator and Photoshop. This would allow seamless design, creation and editing of projects. It remains to be seen, however, how well these PDF-based approaches will integrate into a Quark production workflow.
If you were an output professional, such as a prepress service bureau or printer, you would probably be just as happy with a good PDF from Quark or any other application file created in Distiller.
Another important feature of the new 1.3 version of PDF is the increasing ability to edit parts of the file. Some of this ability has been available in the PDF file format for some time, but the necessary tools have not been readily available. Along with the recent release of Adobe Acrobat 4.0, as well as the new PDF file format v. 1.3, there are many new options on the market. These editing capabilities include limited handling of text, as well as scanned (raster) and illustration (vector) objects through the use of Photoshop and Illustrator. This editability increases the potential use of PDF as a transfer format or even a manufacturing format.
As a transfer format, PDF can be created at the content provider and supplied to the printer in place of application files and their associated pieces and parts. Of course the requirements for an acceptable transfer file go beyond just the formats' features to the actual process compliance of the files. Since the publishing and printing industries still have a significant problem receiving compliant application files, it is still necessary to preflight incoming files.
Owen Wooding, vice president of technology at Eastern Rainbow (Derry, NH), says that most of his design and catalog customers are not comfortable with the prepress aspects of the process, relying instead on his shop's expertise to ensure file compliance to printers' requirements. Eastern Rainbow accepts application files with low-res image placements from most of its clients, then works them into final PDF files to supply to printers.
Gamma One's Scott Tully explains that very few customers send PDF files to the North Haven, CT, facility. "Customers want us to use our expertise to ensure that the pages are shipped to the printer meeting all specified requirements. Our job is to eliminate variables and ensure consistency for our clients," says Tully.
A number of preflight tools have been developed to check and/or automatically correct PDF files. At last count, there were atleast seven preflight applications available.
Currently, the printing of PDF files is supported by all PostScript prepress systems and output devices through Adobe Acrobat. This, in fact, creates a PostScript file that is acceptable to these systems and devices. With the release of PostScript 3 RIPs, however, PDF files are natively supported without any necessary conversion to PostScript or Acrobat.
Almost all of the output device vendors have, or will soon have, an Adobe PostScript 3 RIP implementation or some other clone that supports native PDF files as an input format. Depending on the type of process implementation, this scalability also may affect the available options for many prepress tasks such as trapping and imposition. Currently, native PDF trapping and imposition is limited to a few prepress workflows and several third-party applications. This is, however, rapidly changing as new versions of trapping and imposition software are being released.
Another use of PDF is as an internal manufacturing format. An internal manufacturing format is the native file format used within a prepress output production system. These formats support tasks in the output process such as trapping, imposition and editing. As an internal manufacturing format, Agfa had the first complete PDF implementation in its Apogee product, but Fuji was a close second with its Valiano system and Heidelberg Prepress is actively discussing its new prepress workflow system that will increasingly include PDF as a manufacturing format.
Not to be left behind, systems from Scitex, Barco, Rampage, Screen and others have implemented the seamless integration of PDF into their workflows. This integration allows for many of the benefits of the PDF format to be enhanced with existing prepress systems and tools. In these approaches, PDF files are converted into internal manufacturing formats. In the end, the manufacturing format may not be a big issue as long as the client gets the output expected in a smooth, accurate, timely manner.
Because of limited availability of specific prepress software packages that support native PDF, Eastern Rainbow has opted to use an Agfa Apogee system. However, due to its early stage of development and implementation, Wooding claims to have found a number of tasks slow. Training, of course, remains a key issue that is being addressed over time.
Tully at Gamma One, on the other hand, has developed its own automated PDF prepress processing system using "off the shelf" products.
As with any new technology, printers still must be willing to accept PDF files. Both Wooding and Tully spend much of their time evangelizing PDF to their clients' printers. Today, for example, Gamma One says that about 15 percent of its computer-to-plate (CTP) work is being shipped to printers using PDF. The prepress company shipped its first PDF CTP job in July of 1998, and has convinced about one-third of clients' printers to accept PDF files. The balance of the CTP work goes out as TIFF/IT and a small percentage as film.
Eastern Rainbow currently supplies 50 percent of its output for CTP to printers in PDF format.
Wooding believes printers are more conservative than prepress houses and are reluctant to accept PFD--but will "get there eventually." Another obstacle to adoption is that many of the printers' RIPS can't accept the native PDF files. "While printers can still process the PDF files as PostScript, it is costly in addition to adding a higher level of complexity. It also raises issues of shared responsibility," points out Wooding.
For those who have been working in a pre-separated workflow, converting to and implementing PDF output can be more difficult than for those used to working in a composite workflow, according to Tully. In a pre-separated workflow, image files are usually stored in a multi-file format such as DCS. In this approach, each of the colors (CMYK) exists as either four separate files plus a placement file (DCS 1.0) or as separate pages in a file (DCS 2.0). Once placed into Quark or other layout application, separations are actually printed from that application. In other words, the application creates individual PostScript pages for each color and each page in the file, assigning the separated image files to the appropriate color page.
In a composite workflow, the stored image files are not separated into individual files or pages, but kept as one singular composed file with all of the image color data defined on a per pixel basis within that file. When you place those images into a layout application and then print, you are printing a composed PostScript (all color information combined in one file or page) file that gets separated in the RIP. This usually ensures a less complex, more reliable workflow that is more WYSIWYG, since you are printing a composed file while viewing a composed file on the monitor.
If you want to use pre-separated image files in a composite workflow, you will need to eithercombine the images in an application such as Photoshop or have special extensions that can combine the pre-separated images at the time of the creation of the PostScript file. In addition, some of the prepress workflow systems have special handling provisions to resolve this issue. So if you have a legacy of pre-separated image files, there could be a lot of work needed to make the conversion to a composite workflow.
A complete conversion to PDF workflows also can be hindered by legacy page files and film. Since many of the process files that exist in servers around the world are in some processed manufacturing format such as TIFF/IT, Scitex LW/CT or Heidelberg Delta, files need to be reprocessed to create a PDF. These companies have announced software that converts legacy files to PDF, however editability is somewhat limited. Editing tools such as EnFocus' PitStop can handle some color and even content editing on these files, but text editing is still not possible in these exported legacy files.
Legacy film creates an even greater problem. Film exists as separated colors, while PDF files are composite files. There are a number of workarounds available, however. By scanning or digitizing these films and saving them as either individual screened bitmaps or DCS files (separated PostScript), you can integrate them into a variety of available workflows, along with newly created PDF files. However, it doesn't lend itself to a smooth, consistently reliable and repeatable workflow. Of course, editing is not currently practical on these files.
While each of these issues can create a complex process, most of these legacy problems are short-term transitional issues that will go away in time. The extent of this transition is dependent on the type of work being produced. In addition, many prepress systems offer special hardware and/ or software tools. Finally, in many cases it pays to reprocess pages when files are available to circumvent the problems associated with legacy page files and film.
One of the less discussed, yet increasingly more important uses of PDF, is the "normalizing" of files. This includes files coming from the burgeoning "non-professional" publishing market. This market, which consists of office professionals using Microsoft Office software, is introducing files that are more difficult to process into the output production pipeline. In many cases, the creation of a PDF file produces a stable format that can run through a variety of RIPs and output devices.
So it's fairly easy to see that PDF will offer some significant benefits to the publishing process, from design and page production through output production. Continued development of Acrobat and the PDF file format will ensure a smoother, fuller compliance to all of the requirements of both the print process and Web-based process. In addition, the continued development of third-party plug-ins to Acrobat and applications that will further support and extend the features will foster and increase the use of PDF workflows.
One of the biggest barriers to the adoption of a complete PDF workflow is going to be a cultural one. While the necessary tools will undoubtedly be there, the necessary education that enables people to handle the new output process will take some time. Many of those reluctant to adopt this new technology still have the conversion from conventional production to digital production fresh in their minds--they aren't anxious to relive those experiences.
With the increased adoption of PDF and the process changes that will occur, the roles of prepress will be changing again. More of the process will move upstream to the designer in the form of PDF creation. While even in today's production model there is still a need for prepress houses to use their expertise to handle trapping of OPI, this may be changing in the near future.
With the use of PDF comes the wider use of compression. Once image compression is better understood--and used properly--the need for OPI may wane. Compression also allows PDF to be ideal for handling large-format output, claims Tully. These smaller files not only make it easier to transmit final files for output, but also significantly shorten the processing time for the output devices. Trapping also is rapidly moving into the output RIP engines and is becoming almost transparent. Historically, this task has depended upon the skills of an experienced operator.
Much of the process support given by prepress providers will be relegated to those designers or non-professional publishers that either demand or require assistance to ensure a level of quality or dependability. With PDF, the savvy production designer will now have even more tools that allow them to go directly to the printer.
Wooding cautions, however, that even if his customers supply him files with the high-res images in place, clients are reluctant to provide PDF files because of their concerns with the issues of quality and responsibility. Ultimately it may come down to the need for a certain level of insurance.
PDF will continue to change the print process. As roles change along the publishing/print continuum, issues of responsibility and costs will be challenged--and changed. The rate of change will be related to the comfort levels of those involved and their ability to react to changes.
What to do? Purchase Acrobat and start to learn about how to make it work for you. Then start to work with your staff and customers to develop programs utilizing your expertise to add value to the print production process.