Knowing What to Look For

Editor’s Note: This article is part of the PDF Preflight Learning Center

What is a problem in your workflow might be an advantage in mine. What problems you need to detect during preflight all depends on how you use PDF files in your setup. Just take image resolution as an example; depending on the output technology and materials used to print a job, printers might have widely different ideas on the minimum resolution needed for images.

So, determining that you need to preflight your PDF files is one important realization. But even more important is to come up with the correct set of rules to be used during preflight. That set of rules is often referred to as a preflight profile and most preflight technologies out there allow you to configure preflight using one of those profiles.

In most cases you don’t have to and shouldn’t make preflight rules from scratch. A number of organizations have already spent a considerable amount of time on this subject. The result is a number of standards and specifications that define preflight rules for various scenarios. It is in your best interest to look around at what is out there. Even if you have to customize the preflight rules for your particular situation, start from a standard set of rules for a situation that resembles your own and modify those. No need to reinvent the wheel!

The best that can happen is that a publisher or printer you are going to work with on a project has already developed a collection of preflight rules. Such rules are perfect since they are the rules your publisher or printer will use to validate your PDF files as they receive them. Always take the time to check out their web site and see if they haven’t already done the work for you. An excellent example of such a web site is the Time, Inc web site that contains explanations of what they expect and downloadable preflight profiles for different vendors. Web sites that collect specifications from different printers and publishers can help here too; an example of this is the web site.

If you aren’t that lucky, perhaps an industry association active in your market segment can help. Many industry associations are active in developing guidelines; preflight profiles are often part of those guidelines. Since 2002 the Ghent PDF Workgroup organization streamlines the work done by more than fifteen such industry organizations. Their web site contains a collection of preflight profiles, Adobe Acrobat Distiller settings, Adobe InDesign and QuarkXPress output settings for nine different marketing segments.

Profile Description
NewspaperAds for newspapers, allowing medium resolution, CMYK and/or spot color
MagazineAds for magazines, high resolution CMYK only
Commercial sheet offset printing and digital printing
SheetCmyk CMYK only
SheetSpotHiRes all color printing (including CMYK and/or spot color)
SheetSpotLoRes all color printing (including CMYK and/or spot color), allowing low resolution
Commercial (cold set) web offset printing (newsprint), with allowance for medium resolution
WebCmykNews CMYK only
WebSpotNews all color printing (including CMYK and/or spot color)
Commercial (heat set) web offset printing
WebCmykHiRes CMYK only
WebSpotHiRes all color printing (including CMYK and/or spot color)

If neither of the above helps, don’t despair. There is an ISO standard out there called PDF/X that will serve as a very good base guideline for you to start from. In fact most of the preflight rules mentioned above are built on top of the PDF/X standard.

PDF/X is an internationally accredited standard developed by the ISO (International Standards Organization). What it does is define which features in PDF are usable in print oriented PDF files and which are not. That means that if you know someone is sending you a PDF/X file, you are sure it is much more reliable and has a higher chance to print than if they send you just any PDF file.

As PDF/X is targeted towards the whole print industry it is a very broad standard. Some of the preflight rules you will want to use in your particular workflow are not part of the PDF/X standard. Again image resolution is a prime example; as everyone in our industry has a different idea about the perfect resolution for images the PDF/X standard doesn’t define what image resolution should be. Much more information can be found on the PDF/X web site.

Selecting the preflight rules you will start from and then adjusting them to your unique workflow is very important. It is well worth spending time on this, as the quality of the results you receive during preflight is largely dependent on how good your preflight rules are…

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About the Author: David van Driessche

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