Standardizing File Formats

Prepress professionals continue to push for the standardization of file formats so as to help eliminate ambiguity during the exchange of print-ready material in electronic form.

In the United States, the Committee for Graphic Arts Technologies Standards (CGATS) is spearheading the effort to develop file format standards for the graphic arts. International efforts fall under the domain of the ISO (International Organization for Standardization) and CIP4 (The International Cooperation for the Integration of Processes in Prepress, Press, and Postpress).

"There seems to be increasing acceptance that standardizing on a single file format for each form of use is a good thing to do," says Martin Bailey, Global Graphics Software's senior technical consultant and chair of CGATS SC6. "Currently, many different proprietary file formats are all aimed at slightly different requirements. As organizations struggle to replace these with standards, there's an inevitable appearance of a vast explosion of different standards appearing."

Adds Bailey, "There's a tendency for such organizations to identify a number of similar workflows that actually require subtle, but significant, differences to the content or control files used in them. This is why you end up with PDF/X-1a, PDF/X-3, and the soon-to-be-released PDF/X-2. It's also why there is PPML [Personalized Print Mark-up Language], PPML/GA, and PPML/VDX."

The end result, says Bailey, is that a lot of different formats are now being put forth as industry standards. "There will be an inevitable learning curve, but the end result should be that most users will find a specific set of formats that are carefully designed to meet their needs," he states.

To date, three basic file format standards are in place for the encoding of content data: TIFF/IT (ISO 12639) and the PDF/X family (ISO 15930 Parts 1 to 3) for predefined printing, and PPML/VDX (CGATS.20) for variable-data printing.

"The PDF/X standards are simply PDF with pieces that don't work in prepress cut out and thrown away," says Bailey. "They are therefore far more reliable in prepress, reducing rework or correction time."

PDF/X limits some options, such as the color space that may be used, to ensure that it will print reliably and consistently through all devices with PDF/X-compliant readers.

"All of the restrictions that we put on PDF are to ensure reliability," says David Q. McDowell, standards consultant for NPES The Association for Suppliers of Printing, Publishing and Converting Technologies, and chairman of USTAG/ISO/TC130 Graphic Technology. "If you want a compliant system, you have to be able to read anything defined as part of it. The trick is to keep that compliant system as narrow as possible."

Adds McDowell, "If you are compliant with the PDF/X standard, the receiver will see exactly what you intended him or her to see; with PDF by itself, that is not a certainty."

Tools such as Global Graphics' Overprint Control Strip, which verifies PDF/X-compliant workflows from creation to output, offer further reassurance that PDF/X documents will print as planned.

Here's the status of the PDF/X standard. Both Part 1 (PDF/X-1 and 1a for CMYK data) and Part 3 (PDF/X-3 for CMYK and color-managed data) of ISO 15930 have been published, even as revisions of both standards to incorporate PDF 1.4 compatibility are in ballot.

The final draft of PDF/X-2 (partial exchange) has been prepared and also currently is in ballot with an ISO committee. A new initiative, called PDF/A, revolves around development of international standards that define the use of PDF for long-term archiving of documents.

In the Graphic Arts Technical Foundation's Technology Forecast 2003, McDowell writes that "By the end of 2004, PDF/X will replace the many proprietary object-based formats in use today, and will also replace TIFF/IT in many applications. We can also expect to see PDF/X moving beyond the advertising/publication market into commercial and utility printing markets."

One telling point that PDF/X is gaining in popularity: Last February, to enhance and simplify its workflow, Time Inc. announced that effective June 1, 2002, its preferred file format for submitting digital ads to all its 56 titles would switch from TIFF/IT-P1, PostScript, and DCS 2 to PDF/X-1a.

However, TIFF/IT is far from dead. Even as CGATS and ISO continue their work on PDF/X-1a and PDF/X-3 (and soon PDF/X-2), there has been a resurgence in the use of TIFF/IT in some markets, says Gee Ranasinha, director of marketing for Dalim Software.

Ranasinha says, "With broadband Internet connections pretty commonplace these days, the distribution of larger files is of less issue than the benefits of a format with 100% data integrity."

PDF/X-1a permits inclusion of CMYK-only raster data, encoded in a similar way to TIFF-IT. TIFF/IT is used to exchange raster-based (image) data, whereas PDF/X is used for object-based data, in which the individual objects may be in either vector (line art or textual) or raster data structures.

"A raster file embedded in a PDF/X-1a file combines the predictability of TIFF-IT with the flexibility of PDF," Ranasinha states. "Dalim Software's suite of workflow applications, for example, can interpret vector information, convert it to raster information, and then wrap it in a PDF/X-1a shell with lossless file compression. Or, it can work in an entirely vector-based PDF paradigm, depending on user preference."

Work also is moving forward on other file format fronts.

CGATS.20-2002, Graphic technology-Variable printing data exchange using PPML and PDF (PPML/VDX), was approved last year and, as of December 2002, was accepted by ISO for consideration as an international standard.

PPML/VDX defines a verifiable data format that allows designers and printers to exchange final-form, variable documents electronically. A PPML/VDX-compliant job includes creative content from current design applications and variable information from common database applications.

The standard combines PPML's capabilities for encoding the layout of variable data with PDF's openness, reliability, and soft-proofing benefits. PPML/VDX deals with the exchange of content information as well as data that represents the final look of variable-print products.

Variable-data printing also received a boost from CIP4. Last May, CIP4 released its JDF 1.1 specification, which includes provision for variable-data print functionality, as well as modifications in the areas of color workflow, e-commerce, finishing, and device capability description.

JDF, or Job Definition Format, is designed both for exchanges between companies as well as communication within a single company. Unlike PDF/X, which is aimed at data content, JDF addresses process control issues and addresses processes within the same department, or between planning, prepress, the pressroom, MIS, and so on.

The new specification was developed in cooperation with several industry groups including CGATS, ICC, IDEAlliance, Ifra, PODi, PrintTalk, and UP3i.

"With JDF Release 1.1, CIP4 has developed a backwards-compatible extension of JDF that incorporates feedback from real-world implementation experience," says CIP4 technical officer Rainer Prosi. "That will serve as the foundation for end-to-end workflow solutions in the graphic arts industry."