All About PDFs
What is a PDF?
The Adobe Portable Document Format (PDF) has revolutionized the printing industry and become the universal file format for preserving source document fonts, images, graphics and layout, regardless what application or operating system was used to create the file. PDFs are widely available, compatible, and easy to distribute. PDFs are intended to make sure that your job looks and prints the same no matter who opens the file. However, there are some pitfalls to avoid when making the best PDF possible for use in printing.
Not All PDFs Are Created Equal
One of the myths associated with PDFs is that they are all the same. Nearly all word processing and design applications have the capability to generate PDF files. Like the applications themselves, each of these files can have inherent flaws and limitations.
How you generate a PDF is as important as what program you generate it with. Because PDFs are designed for both print and web use, they can be generated to different standards. If you are not careful, you can damage a layout created perfectly in its native format when generating a PDF. Requirements for PDF publishing are very specific.
Three Common Ways to Generate PDFs:
Save As (Photoshop CS & Illustrator CS); This approach offers the least amount of user customization and has the potential for the most pitfalls. Office applications, the Windows and OSX operating systems themselves and low-end graphics software will give you little to no control over several crucial settings and will not generate viable PDF's. High-end graphics applications, such as Photoshop CS and Illustrator CS, can correctly create PDFs using this method.
Print Postscript and Distill to PDF : This is the best way to create PDFs using graphics applications prior to the Adobe CS applications and QuarkXPress 6, but it can also be complicated, time consuming, and difficult to configure (printer drivers, PPDs, Distiller settings etc.). Files are first output into PostScript (usually by "printing" to a file). Then the Postscript is Distilled into a PDF using Acrobat Distiller.
Export PDF (QuarkXPress 6 & InDesign CS). Some current design applications have an export feature built right into them. This method bypasses Distiller in favor of a built-in PDF export engine that generates press-ready PDFs, provided you know the correct settings. QuarkXPress 6 and InDesign CS offer this capability. (Older applications such as PageMaker require Acrobat Distiller.)
Best Ways to Get Good PDFs
When generating a PDF:
- Convert Spot (Pantone) and RGB colors to Process (CMYK)
- Always embed and subset fonts.
- Set Transparency Flattening settings to the highest settings (when appropriate).
- Turn off color management (except for Photoshop). All color settings should be set to "As Is" or "CMYK."
- If prompted, set Vector Output Resolution to 2400 or 2540.
- Use Binary data format instead of ASCII.
- If using Photoshop, flatten your file first.
- If using a vector-based program such as Illustrator, convert all text to outlines.
- Leave the trapping to us.
After generating a PDF:
- Check the size of your PDF. Is it at the bleed size?
- Check the Document Properties in Acrobat (under the File menu) to confirm that fonts are embedded and subsetted.
- Make a hardcopy proof of your job on your desktop printer to double check accuracy.
Common Errors with PDF:
- Produced by PDF Writer
- Saved using the OSX Quartz Engine
- Saved from Microsoft applications such as Word or Publisher (text and colors are very unpredictable out of these programs)
- Generic settings such as eBook, Screen, or Web
- Downsampled images (High resolution images distilled to low resolution)
- Built at the wrong size
- High Resolution images not embedded (using OPI)
Using an application that is not listed as an accepted file format?
Your application may have the capability to generate a PDF, but it may not be capable of generating a PDF that meets 4-color-printing-specific requirements. Consult your owner's manual to determine if this is the case.
Many manuals contain chapters on such topics as publishing PDF files or preparing files for commercial printing. Read those instructions carefully. We will accept any PDF file that meets our requirements and passes our preflight process, but we can only provide technical support for the applications listed on our website.
PDF/X - What is it and should I use it?
The PDF/X standard was created by the Committee for Graphic Arts Technologies Standards (CGATS) to eliminate many of the variables that lead to common printing problems such as missing fonts, incorrect color space, missing images and overprint/trapping issues. Many applications offer a default setting for exporting PDF files to variations of the PDF/X standard. We recommend following the instructions.