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PDF - Common Errors

 

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Delay is preferable to error.
Thomas Jefferson

pdf error

 

COMMON ERRORS
Most PDF errors can be easily avoided by following the pass4press guidelines. Utilise the downloadable presets in combination with the correct colour profile for the job. Even though pass4press v10 concentrates on InDesign CS4 and QuarkXPress 8, older versions of both can export PDF/X-1as, as can Illustrator – and even Photoshop with a bit of tweaking. You can also make a PDF/X-1a file from a PostScript file – something that can be created on any computer with a PostScript driver and a copy of Adobe Distiller installed. If you’re using a non-standard app, try and match the guidelines in this brochure as closely as you can, but be realistic about the software you’re using: no matter how hard you try, a print PDF is going to be difficult to create from some packages.
PDF/X errors
If you have a PDF which hasn’t been output to the PDF/X-1a standard it can look like it’s riddled with problems. Just re-exporting with the PDF/X-1a box ticked will usually remove most of the errors. The Output Intent is a key part of creating a PDF/X-1a and has to be there for the file to be valid, even though it is in effect just informational. A PDF/X-1a contains ‘flat’ CMYK: the Output Intent field tells the receiver what profile you used to export the PDF and how its content was theoretically prepared; it demonstrates that you’ve followed the correct spec. The Output Intent is set in the Output tab in InDesign or via the Output Colour Setup in XPress. When you open the PDF/X-1a in Acrobat and view the Output Preview, the Output Intent profile is displayed by default at the top of the window.


Document Creation
INCORRECT Page size information
A fundamental problem: the page size must be accurate from the start. Bleed must be set to allow for movement on press: extend out elements around the edge of the page into the bleed area to avoid unseemly white edges should a shift occur at trim stage.
Insufficient offset of CROP MARKS
Crop marks should be set well outside the bleed area, to avoid becoming visible.
Strokes are to thin
Most presses are simply unable to print very thin lines, so pay attention to publishers’ specs.
Gradient Resolution too low
Gradients in vector illustrations or effects like drop shadows need to be of sufficient resolution to avoid a ‘stepped’ effect. Again, check publishers’ specs for guidance.
fonts
Fonts not embedded
The smooth output of text is always better when produced from the original font rather than the rasterised text (ie, turned into a bitmap image). For licensing reasons fonts can’t be freely transferred in an extractable format; embedding fonts in a PDF is a one-way method of making sure all the fonts used on a page are available for reproduction at maximum quality. If fonts are missing or unavailable, they are typically exchanged for Courier, which will not only ruin a design, but upset designers.
overprint/knockout objects
Be sure to use the tools in XPress and InDesign to check for these problems, which can typically cause text to disappear (or appear). The best approach is to avoid altering trapping options, but rather let experts at the printers handle it.
Digital images
Total Area coverage (TaC) Maximum Exceeded
This is where the total amount of ink laid down is more than the maximum allowed by the publication’s printing conditions. It’s another easy one to solve. The colour profile used when exporting a PDF controls the colour across the output CMYK separations: use the correct profile and you’ll never exceed the TAC. Remember that you need to consider the content origination as well: convert your images, logos and illustrations to the correct destination profile before creating the PDF, rather than letting the export process handle it.
Placed image resolution too low
Low-resolution images will look pixellated and low quality. Even if you start with a 300dpi image, make sure that resizing it hasn’t reduced the effective resolution.
Too much compression applied
Overly compressing JPG images may give small file sizes but will also introduce visible artefacts into the image and degrade quality.
Colour and transparency
Contains non-CMYK Elements
RGB is never acceptable in a print PDF, and spot colours rarely so except on covers. If you’ve used reference swatches from, for instance, Pantone, convert them to CMYK before exporting the PDF.
Wrong color space assigned
Set your color management to use the appropriate ICC profile for the job.
File contains transparent elements
This means the file hasn’t been exported as a PDF/X-1a. Live transparency is supported by the new PDF/X-4 format, but widespread usage is a long way off – it will have a big impact on existing workflows and responsibility.
File use PDF v1.4 or later
It might seem like we’re stuck in the past, using a 10-year old 1.3 version of the PDF format, but most of the PDF updates have concerned support for objects unrelated to printing. Contract Hard Proofs
Proof not Produced from the final PDF or the Proof’s Colour space Is too wide
Proofs must be created from the PDF/X file that will be printed, using a RIP/paper combination that accurately represent the printing conditions. Check publisher’s specs.

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