Why are there so many "flavors" of PDFs? How are they different?

Why are there so many "flavors" of PDFs? I thought PDF was supposed to simplify things!

There are very few printing companies that have not already melded PDF into their workflow and more than a few use PDF almost exclusively. But there is a serious catch. PDF has also become the preferred method of transferring cross-platform files across the web. For the web and for most office applications, file size, speed of transmission and universal readability are what matters.

Unfortunately, the resolution and formatting characteristics critical for print production are well beyond the 72dpi RGB needs of monitor viewing. The problem is not really that these files cannot be printed, it is that they can look pretty awful when they are. Graphics that are passable when printed out on the office laser or ink jet printer do not pass muster in commercial print.

The print industry responded by forming a couple of organizations to set standards for using PDF in print production. The Ghent PDF Workgroup (GWG - www.ghentpdfworkgroup.org) and the Committee for Graphic Arts Technologies Standards (CGATS - http://www.npes.org/standards/cgats.html) began working on standards for creating PDF files that would work in commercial print and packaging environments. You'll be happy to know the groups work well together!

PDFX is merely a subset of PDF specifically for high-resolution printing. It became obvious there could not be one standard to fit all applications. Web presses, package printers, sheetfed and digital printers all have specific needs. PDFx1a has been widely adopted by the advertising industry, particularly for magazine advertising. The standard requires font embedding and CMYK images and spot colors, among other things. But other printers wanted a standard that would allow transparency, RGB images, color management and more. For this reason, PDFx3 standards have also been developed. The standards are evolving as new software is introduced, and new capabilities are requested by users. It is likely the evolution will continue for several years and you may see more "flavors" in the future. Adobe allows users of Acrobat Distiller (their engine for creating PDF files) to plug-in their own set of standards for creating the PDF files, and some printers supply their customers with a custom set of standards.

While it may seem complicated, the intent is to automate PDF production so the correct file type gets sent to produce the desired outcome. Acrobat 6.0 has integrated the PDFX1a and PDFX3 standards into Distiller, so creatives and buyers can produce files that comply with the most widely used standards without a lot of in-depth knowledge of what's going on "under the hood." But it does mean that buyers, creatives and printers need to be clear as to what standards must be met when PDF files are originally created.

Stephen Beals is a digital pre-press manager and has been writing for major print publications for many years. He is the author of A Practical Primer for Painless Print Production. He can be reached at stephenbeals@mac.com.
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