DIGITAL PUBLISHING: PDF/X-1a for The Delivery of Ads

Folio: The Magazine for Magazine Management, Oct, 2001 by Linda Manes Goodwin

By using the latest accredited file standard based on the PDF format, publishers and advertisers move closer to error-free digital file exchange. By Linda Manes Goodwin

Many magazines today specify Adobe's portable document format (PDF) as the preferred format for submitting digital advertising materials. Unfortunately, PDF is not the optimum vehicle for delivering final print ads. When a document is destined for press, there is no need, for instance, for complicated animation, video, audio, hyperlinks, security or RGB elements--all of which the PDF format allows. And although a PDF file may be properly prepared for high-end printing, there is no guarantee to the publisher or advertiser that that will happen. But there is a file format that moves everyone a good deal closer to secure and painless file exchange: the PDF/X-1a.

PDF/X-1a was recently accredited by ISO (International Standards Organization), the same group that accredited TIFF/IT-PI. A committee of graphic arts professionals wrote the specification in the hope of creating a "foolproof" vector-based file format for the delivery of final digital ads. Although use of PDF/X-1a does not guarantee a perfect file, it does eliminate many common errors that can happen when files are sent in native application, PostScript or even PDF format.

In order to comply with PDF/X-1a, for example, all color elements must be defined as CMYK, spot or Device N (duo-tones). Publishers no longer have to worry about receiving RGB images that require conversion to CMYK color space, which can alter the appearance of the artwork. Because all graphic elements must be embedded in a PDF/X-1a file and encoded in the format, it is difficult for an advertiser to forget to send them to the publisher. (Anything is possible, but it is unlikely that any graphic elements will be lost in transmission.) Fonts must be embedded as well, eliminating the chance of substitution. And since mechanical marks are required, a publisher knows immediately how to position the ad. PDF/X-1a also allows for a certain degree of color management through the use of an ICC (International Color Consortium) profile; when an ICC profile is used, the intended printing condition is identified. The current set of software tools that writes PDF/X-1a files defines the printing condition as SWOP (Specific ations for Web Off-set Publications). (See "S V/OP Enters the 21st Century," Folio:, May 2001, page 56.)

Since PDF/X-1a is a subset of PDF, anyone working with PDF can use the new standard. Yet because it is a relatively new file format (it was accredited by ISO in May), brand new tools are needed to process it properly. A publisher's raster image processor (RIP), whether driving the proofing device or platesetter, should be able to interpret at least PostScript level 3 and at least PDF 1.3. A viewing application that can show overprints correctly, such as Acrobat 5.0, should be part of the workflow, as well. And publishers should upgrade to Acrobat 5.0 or PDF 1.4. PDF 1.3 will not show overprints.

Currently, some tools for under $200 let users write, preflight, verify and process vector PDF/X-1a files. McCann-Erickson, Time Inc, and The LTC Group, in fact-in conjunction with the Digital Distribution of Advertising for Publications organization (DDAP)--recently worked together to test a complete PDF/X-1a workflow. Apago's PDF/X Checkup 2.0--an Acrobat plug--in that checks for adherence to the spec, issues a report on violations and automatically fixes many of them-was used to write the PDF/X-1a file. And Enfocus just released a new product, Instant PDF, that writes, preflights, autocorrects and tracks changes to a PDF/X-1a file.

As with any new workflow, it's important to test PDF/X-1a thoroughly. And don't be afraid to make the change; such publishers as Easy Riders, Inc., Wizards of the Coast, Inc. and US News & World Report Inc. are designing and testing PDF/X-1a. Whatever the file format you are currently using, the adoption of PDF/X-1a will improve your workflow. It offers the security and reliability of a standardized file format, yet the flexibility of vector-based data.

Linda Manes Goodwin is a print production consultant E-mail her at linda@manesgood-win.com

DIGITAL PUBLISHING: ASK THE EXPERT

When our advertisers produce PDF/X-1a files, should they use the generic ICC TR001 profile or our company's custom version of TR00l? Our company's custom version is produced using actual press curves from our printer.--John Dunn, production director, Wizards of the Coast Periodicals.

Barbara Hanapole, executive director, Digital Distribution of Advertising for Publications Association, answers: In a profile, there are two lookup tables. One defines the data values in terms of LAB color imagery. This is employed when the profile is used as a source file. The second shows how to convert LAB values into CYMK. This is employed when the profile is used as destination table.

In any properly made PDF/X-1a file, where all the data is CYMK, the "Output Intents" file defines the CYMK to LAB translation. Since the TR001 profile is identical to the lookup in the CYMK to LAB table, it does not matter which profile is used.