Adobe Acrobat gets better and better at preflighting PDF files for resolution, fonts and color. But with Photoshop, Illustrator and a little ingenuity, you can preflight all these things without the usual preflighting tools.

I used to work at a small publishing company. I was responsible, among other things, for preflighting camera-ready advertisements that came in PDF format, created by ad agencies, freelance designers, secretaries, small-business owners and their kids. This experience taught me a lot, but these lessons really stand out:

• No one seems to use [1] PDF/X-1a, or even knows what it is
• A camera-ready PDF will pass printing requirements only one time out of five
• Of the other four that didn’t pass muster, three times out of four you won’t be able to teach the designer how to pass the requirements at all
• It’s just as likely a bad PDF will come from an ad agency than come from a newbie
• It’s possible to preflight PDFs without Acrobat preflight tools or a third-party plug-in

I learned this one the hard way, because the design department used [2] Enfocus PitStop Professional to preflight PDFs, but the current version did not support OS X Tiger 10.4 (although [3] it does now with the 6.51 upgrade). I used Tiger; all the other designers were using Panther 10.3. And I was only using Acrobat 6, so the Print Production toolset wasn’t available. It seemed like I had only enough rope to hang myself. So my choices were to either harass the other designers to do the job for me, or learn a way to do it myself without PitStop or Acrobat 7.

It Can Be Done

Preflighting PDF for print publishing is not too difficult because there are only three major requirements:

• Embedded fonts
• CMYK color mode (if you’re doing standard four-color process)
• Minimum resolution (170ppi for newspaper, 300ppi for magazines)

If you have all three, your PDF is going to print well for most conventional print jobs. In this How-To, I’ll point out the various ways to preflight for each of them.

If you are also interested in Acrobat’s preflighting tools, [4] check out Elisabetta Bruno’s article on the subject.

Are the fonts embedded?

“Embedding” is the process of inserting a font file inside a PDF. With a properly embedded font, the PDF will display the right typeface no matter what computer it’s displayed on. If the font isn’t embedded, the PDF may resort to displaying an alternate typeface or simply default to the beloved Courier (those of you working with daily newspapers know what I’m talking about). You can embed a complete font file or just embed a subset of the font characters used, leaving out the unused characters and thus making a smaller PDF.

Figure 1: The PDF’s fonts, as shown in the Document Properties dialog box.

Preflighting the fonts is probably the easiest of the three requirements to check, because Acrobat has a nice collapsible overview of font usage in its Document Properties dialog box (File –> Document Properties…, or Cmd-D/Ctrl-D). Click the Fonts tab in the Document Properties dialog box and you’ll see a list of fonts (see Figure 1 for a detail). Figure 1 shows several fonts in various degrees of embeddedness:

• Embedded fonts: Optima, Optima Bold, Optima Oblique and ZapfDingbats are marked as “embedded subsets”. These fonts will print properly. If the fonts were embedded entirely, they would be marked as “embedded”.
• Unembedded fonts: Minion Regular is not embedded. Fortunately, I have Minion Regular on my computer and so Acrobat uses my copy as the “actual font”. This font will print properly unless the PDF file is printed from a different computer without a copy of Minion Regular.
• Replaced fonts: Optima Italic (which I suspect is just Optima Regular faux-italicized by the page layout application) is replaced by Adobe Sans MM, which is Acrobat’s favorite serif font and is used whenever a serif font is missing.

I find it very difficult to preflight fonts any other way than with Acrobat’s Document Properties dialog box. Illustrator will warn you of replaced fonts (see Figure 2) but gives no inkling to this file’s other problems. Photoshop simply rasterizes the fonts and doesn’t give you a warning at all.

Figure 2: Illustrator can warn you of missing fonts.

Is the color CMYK?

Adobe Acrobat 7 has some great tools for preflighting color (I refer again to [5] Elisabetta’s article). However, if you haven’t upgraded for some reason, there are three techniques I used to preflight color.

Acrobat’s Advanced Print Setup. It might surprise you, but Acrobat has had a very robust Print dialog box for quite some time. You can manage inks (similar to InDesign’s Ink Manager), set marks and bleeds, change Transparency Flattener settings and fiddle with PostScript options. All these features are buried in the Advanced Print Setup dialog box. When you select File –> Print… (Cmd-P/Ctrl-P) click the Advanced… button to see the Advanced Print Setup dialog box. Once here, follow these steps:

Step 1: Choose “Output” in the submenu on the left side of the dialog box.

Step 2: In the Color drop-down menu, select “Separations”.

Figure 3: Finding a fifth plate with Acrobat’s Ink Manager.

Now the Ink Manager settings are available to you. As in InDesign, you can see all the plates in the document, turn them on and off and actually see the results in the thumbnail view. In this example (Figure 3), there is a second black plate that has most of the copy; I’m not sure why. You can click the Ink Manager button and alias inks or convert spots to process colors, but from a preflighting standpoint we now know this file isn’t quite four-color process.

Open bitmap images in Photoshop. If it’s an image that you question, an easy trick in Acrobat is to Option-double-click on an image with the TouchUp Object Tool (the icon is a mouse cursor superimposed on a box). The image is then imported into Photoshop and the color mode will tell you if you have a CMYK or RGB image in your file. If all the images are RGB, it’s likely the file was converted to RGB during the distillation process; almost any time you find an RGB image, every image will be RGB.

Open vector images in Illustrator. The TouchUp Object Tool doesn’t just work on bitmaps. Option-double-click on a vector logo, type or other vector graphic and it will be opened within Illustrator. Illustrator will display the color mode on the title bar, and you can also use the Eyedropper Tool to check specific colors, even spot colors. In Figure 4, you can see CMYK listed in the title bar, but the text reads as “5th plate black”.

Figure 4: Illustrator will also show you a lot of color information in a PDF.

Is the resolution nominal?

Resolution is something every designer asks about beforehand (”What resolution do you need?”), but a lot of PDFs don’t meet the resolution requirement anyway. Like color, resolution is something that can be ruined during the distillation process by downsampling. Distiller preferences can be set so the PDF is optimized for screen or proofing, and lowering resolution is often a part of that process. Images may be 300ppi when placed in the layout, but once the PDF is created that resolution is thrown away in favor of something like 72ppi (standard web resolution).

Of course, vector graphics are resolution-independent so that means Illustration isn’t needed to test resolution. What we need is Photoshop. Using the TouchUp Object Tool technique described above, you can not only verify an image’s color mode but also its resolution. Just select Image –> Image Size… and you’ll see the image size and resolution. If resolution is low, it’s time to call the designer.

Figure 5: Ever seen the movie Innerspace?

Every now and then, you may see an image with size and resolution similar to what’s shown in Figure 5: an unbelievably small image size with an unbelievably high resolution. I’m not sure why this happens, but in my experience PDFs that exhibit this trait often come from the same designer over and over so I think it has something to do with the PDF creation process. There may be a distillation technology that causes this. I’d have to do some testing to find out for sure. In any case, the one way I know to get around this is to measure what the image size is in the PDF (in this case, it’s supposed to be 8.5″ wide) and input that in the proper field while “Resample Image” is unchecked. The numbers should make a lot more sense after that. In this example, it says my image has 150ppi resolution at the printed size, which is nominal for newspapers but low for most high-quality printing situations.

Don’t use these techniques if you can help it

It sounds odd, but the techniques described above should really be thought of as Doomsday weapons, used for Prepress Armageddon. There’s so many great PDF preflighting plug-ins and software out there, and Adobe has been stocking Acrobat with more and more preflighting and prepress features with every upgrade, realizing now that PDF’s importance in print publishing has overtaken its original role as a vehicle for on-screen content. Acrobat alone can get you through most preflighting situations, and if you can get some designers to use PDF/X-1a, then your job is done for you. But if you find yourself in a situation where PDFs are coming in particularly dirty, and standard PDF preflighting tools just aren’t available to you, remember that Photoshop, Illustrator and Acrobat itself can tell you all you need to know in order to take that PDF to press (or, more likely, right back to the designer).