Wisdom of the PDF Sage

According to the Desktop Publishing glossary of terms, Overprinting is defined as:

Definition: In most cases, when two objects of different colors overlap they knockout — they won’t print on top of each other. To intentionally print one layer of ink on top of another is to overprint. Overprinting is sometimes used to avoid the need for trapping and avoid gaps between touching colors. Spot colors intended to designate the application of spot varnish are also set up to overprint.

But if you ask me - it’s just the biggest pain in the printing industry’s derriere.

The reason that it is such a nightmare for designers is that the act of overprinting only makes sense on high end printing devices - it doesn’t make sense on a computer screen or the average home/office printer. As such, for the longest time, designers had to print to see if they were doing their design correctly.  Fortunately, Adobe introduced "Overprint Preview" into Acrobat and our authoring applications so that you could see what going on, on screen, while authoring and with the finished PDF.

Unfortunately, for the longest time, only Acrobat itself could preview Overprint. It wasn’t until Reader 7 that the feature was added to Adobe Reader - and then, like Acrobat, the option/preference was OFF by default.  Designers, printers and the like had to make sure that they had their preferences set correctly and provide their users with proper instruction.  

With Acrobat 9, we decided that enough is enough! Designers need to know that users, whether they are using Acrobat or Reader, regardless of their preferences, see what is going to print.  Isn’t that a big reason why people use PDF??  

In designing this feature, we originally planned for it to just be completely automatic and appear only when a PDF had the necessary components. However, we discovered that there are many files out in the world that weren’t really supposed to be printed, and thus generate a "false positive" and produce inaccurate renderings. What is worse, is that 99% of these "false positives" are PDFs authored using a well known competitor to Adobe’s products - and we didn’t want to be seen as "playing favorites" with the quality of document rendering.

So we did the next best thing!  We went looking for a clue in PDF documents that demonstrates that they are - without a shadow of a doubt - destined for printing. That "clue" is compliance with PDF/X (ISO 15930)!  Since PDF/X is a standard designed for the creation of PDFs for blind exchange in print production - we can clearly say that all such files SHALL have Overprint Preview enabled.   And that’s exactly what Acrobat/Reader 9 does.   As part of it’s PDF/X Conforming Viewer implementation, when it detects that a PDF is compliant with PDF/X - it makes sure that overprint is properly rendered to screen.

We did, however, leave the preference in place - so that if you really want to turn Overprint Preview to "Always" or "Never", you are welcome to do so. We also left in that original "Automatic" option for anyone wanting to experiment and see the results.

Everyone in the print/publishing community that I’ve talked to is really excited about this feature…I hope you will be too!

This entry was posted on Friday, June 13th, 2008 at 6:40 am and is filed under Acrobat 9. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.