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PDF: Is It Soup Yet?

Apr 1, 1998 12:00 AM


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It's now been well over a year since Adobe Systems released Acrobat 3.0, the application that was supposed to make Adobe's Portable Document Format (PDF) become the "digital master file" for much of our prepress workflow. During these 14 months, there have been a rash of magazine articles, books and seminars touting PDF.

Today, however, the question remains whether PDF is ready for prime time. Is PDF ready to take the baton from PostScript and be the new de facto standard for transferring digital artwork used for four-or-more-color printing? Is it soup yet?

The short answer is "not quite," though a "yes" answer is not that far away. Conventional wisdom among industry pundits is that it will be another year, give or take a few months, before a full, uncompromising PDF workflow is available.

Nonetheless, PDF is being used very effectively in black-and-white. According to Sarah Rosenbaum, Acrobat product marketing manager for Adobe, Associated Press' AdSend digital ad distribution service is now transmitting more than 100,000 ads per month in PDF format. And up to 20 percent of those are said to be in color. Beyond this, there are a number of leading printers and prepress houses that have been able to make PDF work for process color--on certain jobs, with certain customers. But, in terms of having a PDF workflow take over everything that passes through your shop, we are not quite there yet.

Before going further, let's first review the components of the Acrobat product. The Acrobat Reader allows users to view PDF files for soft proofing or on-line reading, then to print acomposite file to a desktop printer. Though shipped as part of Acrobat 3.0, it is widely available free of charge. In terms of a prepress PDF workflow, however, the two primary components of Acrobat are Exchange and Distiller. The Distiller component is the software that actually converts "fat PostScript" to a streamlined, more easily interpreted file format. Distiller, in essence, is preRIPing files, embedding font information, throwing out unneeded parts of graphics and file layers, down sampling images that were scanned at excessive resolution and applying compression algorithms when instructed to do so--all in order to give users a smaller, more predictably imaged final file.

Exchange, on the other hand, is the Acrobat component that allows users to mix and match PDF pages within a particular PDF document, make limited type corrections and act as a platform for either printing PostScript or exporting pages as EPS files.

Why would printers want to take a look at PDF in the first place? Doesn't PostScript work just fine?

Though the industry has seen an incredible evolution in the effectiveness of PostScript workflows in the past 10 years, there continue to be vexing issues. PostScript output is still highly dependent on how customers design their jobs. Because it is not easily editable, many shops have continued to insist that customers supply the original application files, i.e., Quark Xpress and PageMaker documents, rather than the pure PostScript output that can be printed from these applications. This way the prepress service provider can more readily make last minute corrections to type and fix errors in how the file was constructed.

Receiving the application files can create its own problems. One would be hard pressed to find a single prepress operation that has not experienced a situation in which a job on a tight deadline comes in, is prepared for output, and lo and behold, a font or a graphic element is missing. Virtually every shop has handled files that seem to be in good order but just won't RIP. What Acrobat can do--more specifically, running Distiller and creating a PDF version--is to provide a file that is more certain to have all the font and graphic information. Additionally, the file is "normalized" to minimize RIPing hiccups when imaging film or plates. Unlike PostScript, PDF can be easily viewed on screen for soft proofing, though screen redraws of large files can be painfully slow. An additional benefit is that the resulting file is typically much smaller than would be the case with PostScript.

So then, what's holding things up? To answer this question, we spoke with a number of graphic arts professionals who have effectively used PDF in their production workflows for four-or-more-color jobs.

Owen Wooding, vice president of technology at Eastern Rainbow, a New Hampshire-based trade shop, was already looking at PDF as a burgeoning technology when one of his clients came to him with a possible application. S & S Worldwide, a large catalog production company, had decided it wanted to move work in the direction of CTP. However, S&S didn't want to lose the comfort of having Eastern Rainbow do its prep work.

The question then became what file format to use when packaging work for eventual shipment to the client's printer, Quad/Graphics. Wooding met with Quad, as well as another trade shop that was servicing the same client. Quad's initial inclination was to propose using TIFF/IT, the "fixed" raster and linework file format that certain industry standards committees have been endorsing. However, Wooding had issues with TIFF/IT.

For one thing, Eastern Rainbow would not be able to proof TIFF/IT directly to its Polaroid PolaProof digital halftone proofer. Although the shop could have proofed from Quark to the PolaProof, it would then not actually be proofing the final data going to Quad/Graphics.

When Wooding suggested going with PDF, he was not quite certain how it would work. Though it did work in the end, the company would probably not have tried going in this direction if it hadn't had the liberty to test the process over the course of a few months. The problem was a lack of existing documentation or information on how to incorporate PDF into the company's existing workflows. Notes Wooding, "It was all about trial and error, and that included lots of errors!"

The biggest overall issues revolved around fonts, trapping and maintaining black overprint settings from Quark. The process also was very sensitive to print driver and PPD combinations.

Once a PDF file is created, Eastern Rainbow then saves it as an EPS file from Acrobat Exchange, since the EPS can feed both its PolaProof as well as Quad's Creo platesetter. For a large-page-count document, this can be time consuming, as Exchange only saves one page at a time to EPS.

In terms of trapping, Wooding was able to find a way to maintain black overprint, again with much trial and error, by using a special Quark Xtension--there is currently no way to maintain other trap settings from Quark. To understand why, we spoke with Agfa's PDF evangelist, Michael Jahn. According to Jahn, the big issue has to do with composite versus non-composite workflows--Acrobat uses the former while Quark, Illustrator and many other applications use the later. Quark doesn't write any trapping information until separations are actually generated by the application. Thus, in a Quark-to-PDF workflow, there is no way to directly create color traps in the initial PDF file.

Jahn notes that this composite versus non-composite issue effectively makes it impossible to work directly with effects such as duotones in PDF today--unless you create individual PDFs from preseparated PostScript files. It is Jahn's belief, however, that the next version of PDF might honor use of non-composite duotones, though this would require Adobe to provide a new type of color space support to accomplish this. (Note that while the current version of Acrobat is 3.0, the current version of the actual PDF spec is called 1.2.) Alternatively, Jahn suggests that we might see plug-ins or changes to applications so that a program such as Photoshop could generate a duotone that PDF can work with. Other limitations of PDF that are related to this composite workflow are the inability to represent and display features such as diecuts, bump plates and varnishes.

So what to do about trapping? Eastern Rainbow's Wooding notes that the firm can always take the EPS file generated from the PDF file and run it through a product such as Imation's TrapWise. Others point to the ability to send the PDF file to existing in-RIP trapping solutions such as Scitex Full Auto Frames.

Agfa, which is already shipping a PostScript 3 RIP, has OEMed Adobe's in-RIP trapping technology and may have a shipping product at this time. According to Jahn, the product will include a plug-in for both Quark and for Exchange. This plug-in allows users to select an area of the page and apply specific area-to-area traps. "Though it wasn't designed to replace things such as very high-end packaging applications, for most commercial applications--FSIs, catalogs and magazines--the Adobe in-RIP trapping works very well," claims Jahn. This trapping technology will be part of Agfa's full Apogee workflow system, and, with the RIP, will ship with a preview mode that allows users to actually see the traps before imaging and to view pages with separations turned on and off.

Because of the issues around trapping, some shops are being selective about which customers and types of jobs they are choosing to migrate towards a PDF workflow. For instance, Banta just took its first full magazine, The Southwesterner, a college alumni publication, to press using only composite PDF files. In this case, the client was using PageMaker on a PC to generate its page layout.

Unlike Quark, PageMaker works in a composite mode when applying traps. Thus, the resulting PDF files actually pick up the trapping information from the layout program. Additionally, many early adopters claim converting work from the PC platform to PDF can make many of the typical font headaches go away, as long as the customer is using Type 1 and not True Type fonts.

This particular project was spearheaded by Kevin Zimmerman, manager of electronic prepress for Banta Publications, Kansas City. "My focus [in looking at PDF] was on the really tight turnaround we currently have on our three imagesetters." But like others, Zimmerman had to do quite a bit of trial work before he felt comfortable doing a live job via a PDF workflow. In fact, he reports that he and a colleague spent the better part of a month testing the process before running the alumni magazine.

Zimmerman began looking into PDF after discovering Lantana's CrackerJack product during Print 97. CrackerJack is a plug-in to Exchange that allows users to print separations from a PDF file. For those whose RIP can't handle composite PostScript, such a tool is necessary to make the whole process work.

Banta's situation is different from that of Eastern Rainbow in that the larger company is placing the responsibility for generating the PDF file on the customer. Zimmerman claims that after proper training and "Print Style" configuration within PageMaker, customers can print directly to a PDF, with distilling taking place in the background, thus not creating extra work for customers. In exchange for taking over this part of the process, customers could very well see their film output costs decrease.

Some printers are overtly using price discounts as an incentive for customers to submit PDF files. One of them is Philadelphia-based Baum Printing, a Wallace Company. Because PDF files reduce the need for intervention and last -minute problem solving, the company is generally offering a 25 percent discount on prepress pricing, according to systems manager Henry Wagner. In terms of bringing customers on board, Baum has driven the process. "Much of the cost, expense and labor now falls on clients," says Wagner, "but if they go to multiple printers with their work, PDF gives customers greater consistency and reliability." He cites particular advantages with PDF for black-and-white and two-color manual documentation work. Microsoft Word is often the application of choice for these pages, and because Word works in an RGB color space, separations from such a document will normally print black as CMY.

Wagner notes that Baum's work with PDF might not have been possible without an Acrobat plug-in product called Pitstop from Enfocus. "This is a vital tool to our workflow," notes the systems manager. "It adds Freehand-type graphic and text inspectors to the palette, allowing you to edit colors, perform clipping paths, subset text and perhaps other things we have yet to explore."

Client submission of PDF files is predicated on the customer using the specific Distiller parameters provided by Baum. This includes embedding all fonts with the "subset" command turned off, no image compression, and use of the special prologue.ps and epilogue.ps files. These are files that must be moved into the main Distiller folder after installing the Adobe software and also specifically called for in the Distiller settings. If not done properly, spot colors will be converted to CMYK in the final PDF file.

Such settings open a can of worms. Take the font "subset" issue. Distiller allows the user to embed only that part of a font set that is used in the document, thus making for a smaller PDF file. However, if printers then want to edit text in that PDF file at a later stage, they can only do so to the extent that the needed characters are in the "subset." This is why Wagner suggests customers set "subsets" to "off."

On the other hand, PDF experts such as Dave Warren, systems analyst at Quebecor Printing (Kingsport, TN), disagrees. He chooses to let Acrobat subset everything. Subsetting actually renames the "partial" font set when embedding it in the PDF. Without the renaming, it is possible that the printer's own workstation can quietly substitute the customer's fonts with a different version of the font that happens to share the same name.

Additionally, Warren, in his instructions to customers, tells them to trash a file called "superatm.db,"which Acrobat automatically installs. This file also can lead to font substitution. The obvious risk of such substitution is text rewraps and reflows after the fact.

Warren, too, suggests that customers not use any compression of CMYK images, though he has had good experience with Distiller's JPEG compression of grayscale bitmaps and CCITT Group 4 compression of monochrome bitmaps. However, he and others do concede that it is probably safe to use JPEG low compression on CMYK images, but only after first working through test trials with each customer on an individual basis.

It seems that the generally accepted settings for Distiller are contained in a PDF file for all to see on Jahn's personal web page--www.jahn.org. While Baum's Wagner provides customers with printed "how to" instructions on using Distiller, Quebecor's Warren supplements this with a special ".ps" file that, when stored in the Distiller folder, automatically sets most of the Distiller parameters. Future versions of Distiller should let the user select from multiple stored settings, though that is not currently possible. Those programming-savvy printers who want to supply such a settings file to customers should consult the file DISTPARM.PDF that ships with Acrobat.

In terms of actual project experience, Quebecor highlights a job it did for ICN Biomedicals. It was a 2,240-page catalog with 13 different editions. Though predominantly black-and-white, there were 132 pages of four-color. This particular customer still uses Ventura Publisher, and going PDF eliminated much of the "mess" associated with typical PostScript generated by this layout package.

Using the settings file provided by Warren, ICN was able to reduce the size of the job from 1.5 GB of data to just 30 MB. Since individual sections were much smaller than that, the client was simply able to transmit sections of the job using FTP to Quebecor as they were completed. In the past, the client had to ship the job on expensive optical drives.

Quad/Graphics also has been extensively experimenting with PDF. Gary Lundberg, corporate imaging manager, believes, "PDF submission is somewhat like CTP was two or three years ago--a powerful emerging technology with possible pitfalls. It is a technology for early adopters who aren't afraid to develop a new workflow."

Quad has effectively been processing PDF files for well over a year. The fact that the printer does almost exclusively CMYK printing, without much call for additional colors, has made the transition easier. "Any customer currently sending a PostScript file should consider sending us a PDF instead," boldly asserts Lundberg.

Quad RIPs most of its files through its Scitex PS/2 and Brisque RIPs, which are able to handle the trapping of the PostScript generated by the PDF file. In the case of Creo output, Quad sends PDF files to Creo's PreScript, but trapping through this workflow is considered to still be in test mode. If Quad wants to apply Scitex trapping prior to going CTP, files can be sent to the Brisque and then through Shira or Creo CEPS-to-PostScript conversion to feed the Harlequin RIP in front of the platemaker.

Imposition is another matter. Lundberg says the simplest way to impose jobs is by saving PDF pages as EPS files and then pulling them into a program such as ScenicSoft's PREPS. Alternatively, PDF files can go through Creo's front-end to generate separated PostScript files, which can also feed PREPS. In terms of imposing native PDF, according to Imation Publishing Software marketing manager, Karl Evert, PressWise 3.0 accepts native PDF in addition to EPS and PostScript. ScenicSoft president Erik Smith notes that PREPS 3.5, which is in beta, is also able to take native PDF files, in addition to its existing file formats. He notes that it will be able to support the in-RIP trapping found in some PostScript 3 RIPs.

What needs to happen, then, for PDF to move into widespread use? Lee Webster, one of R.R. Donnelley's resident experts, has identified two issues--getting PostScript 3 RIPs with in-RIP trapping and getting an upgrade to PREPS that would allow the importing of native PDF. So, to some extent, it seems as if the major missing pieces may be right around the corner.

An interesting note is that PDF files are currently limited to a dimension of no more than 45 inches x 45 inches. So, the idea of representing a full flat or a large format piece as a single PDF page is limited to those dimensions. Additionally, there are some inherent limitations within the PDF technology that stand in the way of making a large PDF flat by combining several smaller PDFs. One source indicates that because of the way PDF uses cross reference tables to keep track of page elements, there would be no way to rationalize several of these tables within a larger file.

Ultimately, the approach that Agfa and ScenicSoft appear to be taking is to have the imposition program simply generate the instructions in Adobe PostScript Job Ticket Format (PJTF), telling the RIP which PDF pages to pick for the imposition and where to put them. PJTF is a central part of Adobe's Extreme RIP architecture (as well as the Adobe printing architecture to support PDF printing in other printing systems), but word has it that certain elements are behind schedule.

A final gray area is in the use of OPI with PDF. According to Donnelley's Webster, the PDF workflow is "still a little too flaky for OPI. We are only doing PDF with high-res files at present, though if JPEG compression catches on, we may no longer need OPI." Quad's Lundberg states that the company is just starting to test OPI and PDF. For this reason, Quad is not pushing PDF for customers using Quark on a Mac platform--unless customers have full control of their high-res data.

David Wolz, digital publishing product manager for Sells Printing, is excited about what PDF offers, but in his shop OPI is a "no go" at present. It appears that PDF only supports OPI 1.3, and Sells' ColorCentral OPI server is based on OPI 2.0. One can assume that either Adobe or Imation will eventually address this issue.

Is it soup yet? It really depends on your particular work and customer requirements. Though Acrobat and PDF technology may not yet constitute a hearty and filling stew that will totally satisfy all your prepress hungers, it certainly has been simmering long enough to be worth a taste.

We thought it might be interesting to see what other vendors had to say about PDF today, particularly given that they all seem to have previously pledged their support to the file format. States Axel Zoller, marketing director for Heidelberg Prepress, "We've made it clear, in words as well as action, that Heidelberg is in full support of PDF development. However, as of today, PDF has not been adopted to the extent the industry expected just a year ago."

A somewhat different spin was put on the subject by Marc Johnson, product marketing manager for Scitex America. "We look at a PDF file in the same way we look at a PostScript file--it's just another vehicle to move work from one step in production to the next. Our Scitex Brisque workflow will work equally well with PostScript, PDF or TIFF/IT, as it's able to take in any combination of such file formats for RIPing, trapping, imposition and output."

Finally, in speaking with Arlene Karsh, product marketing manager for digital printing and publishing at Harlequin, we were told that "PDF is a perfectly good file format with some significant advantages as we move forward, though it is in a position today that is similar to where PostScript was in the mid '80s." Furthering that analogy, Karsh posed the issue in these terms, "I, as a user, have tools that work with PostScript now. What can I do with PDF to improve what I am already doing?"

She notes that Harlequin has been active in standards committee work and that CGATS is working toward making TIFF/IT and PDF complementary. Additionally, she adds that the CIP3 committee is looking at whether PDF should be the basis, rather than PostScript, for CIP3 features and functions. However, much of this will have to wait until the next version of PDF is available.

Finally, Karsh argues that although the current version of PDF can work, you do need some consistency in the type of workflow and are limited in trapping and imposition. One still can't place PDFs in Quark, there are issues with nested PDFs and one still hears about problems with fonts. In closing, the marketing manager explains, "We live in a complex world where you can't always anticipate what is going to come from the customer. PDF has a place and potential, but longer term it has to prove its value in terms of price, performance and quality."