Question:
We send our files to our printer via PDF files. We have done this for two years without incident. Last week we had a problem with some perfectly good hi res files which became soft or low res during the PDF distilling process. The file went from 300 DPI to 150 DPI during the distilling. Why did this happen?

R.W.

Answer:
The only explanation that comes to mind is that somehow your Distiller settings were changed. It is possible the preferences became corrupt, but that seems unlikely. It would seem most likely that an operator inadvertently changed the settings in Distiller.

The best way to avoid a future reoccurrence of this problem is to use PDF Certification software like Enfocus CertifiedPDF to check all of the specifications of the PDF file before it goes out to the printer.

You don’t say what version of Acrobat Professional you are using, or whether you are using some other software for distilling your files. Acrobat Professional 6.0 allows you to specify PDFX1a or PDFX3 settings. These settings would not allow Distiller to process the job if the image resolution was less than 300dpi.

You might also want to question whether the original files were actually “perfectly good high res files.” Images imbedded in Illustrator eps files, for example, could be low resolution, or there could be screen grabs in the file. Using preflight software like Markzware Flightcheck will examine all of the objects within the file to make certain everything is up to your standards. By the way, increasing the resolution of screen grabs is generally not a good idea. They are likely to look worse when the resolution is increased than if you just leave them alone. It’s a bit of a Catch22: you may need to increase the resolution of your files to pass the Certification process, only to end up with a file that doesn’t look as good.

But that doesn’t appear to be what you have encountered. The crux of your question is whether a high resolution file could be converted to low resolution in the Distillation process. The answer is yes. It could happen, but only if the preferences were changed or corrupt. If you are on a Mac platform, running a program to restore permissions could fix corrupt settings. To do so, launch Disk Utilities, click First Aid, and check Restore Permissions. If the settings are truly corrupt, and this doesn’t fix it, you might need to reinstall Acrobat Professional.

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.