Guidelines for Creating Print-Ready PDF Files
By the time you submit a PDF file to a printer, the die has been cast. A printer can coax a quality printout from some less-than-optimal PDF files, but for the most part the printer is restricted by decisions made during the creative process. Following these guidelines, you can deliver the strongest, highest-quality PDF file to a printer.
- Remember that the end product is only as good as its components. For high-quality printing, a PDF file must contain the appropriate images, fonts, and other components.
- Convert only when absolutely necessary. Every time you convert text, objects, or color, you compromise the integrity of the file. Therefore, the printed product will most closely resemble your original intent if you minimize conversions. Keep text in its original form, as fonts, rather than outlining or rasterizing it. Keep gradients live. Maintain live transparency as long as possible. And don't convert colors from device-independent or high-gamut color spaces (such as RGB) to device-specific or low-gamut color spaces (such as CMYK), unless advised to do so.
- Use transparency efficiently. Transparency comes into play any time you apply a blending mode or change the opacity of an object. For the best results, try these techniques:
- Keep transparency live as long as possible.
- Place objects you don't want the flattener to affect (such as text and line objects) above all nearby sources of transparency, preferably on a separate layer.
- Use the highest-quality flattener settings when you flatten transparency.
- Proof and preflight before creating the PDF file. Early in the workflow, you have more context for problems, and more options for fixing them. Carefully proof the content and formatting before creating a PDF file. Additionally, if the authoring application provides a preflight feature, use it to identify missing fonts, unlinked images, or other issues that could result in problems down the road. The earlier you can identify and fix a problem, the easier and less expensive it is to fix. Certainly, technical problems found while you're still working in the authoring program are easier to fix than problems found in Acrobat or on a printing press.
- Embed fonts. To minimize the chance of complications, embed fonts in the PDF file. Read the end-user license agreement (EULA) before purchasing a font, to ensure that it permits embedding.
- Use the appropriate PDF settings file. When you create the PDF file, make sure that you're using the appropriate settings. The PDF settings file determines how image data is saved, whether fonts are embedded, and whether colors are converted. By default, Acrobat PDFMaker in Microsoft Office creates PDF files using the Standard settings file, which doesn't meet the requirements for most high-end printing. No matter where you're creating a PDF file for professional printing, ensure that you're using the Press-Quality PDF settings file or the settings file recommended by your printer.
- Create a PDF/X file, if appropriate. PDF/X is a subset of the Adobe PDF specification, and it requires that PDF files meet specific criteria, resulting in more reliable PDF files. Using PDF/X-compliant files eliminates the most common errors in file preparation: fonts that aren't embedded, incorrect color spaces, missing images, and overprinting and trapping issues. PDF/X-1a, PDF/X-3, and PDF/X-4 are the most popular formats; each is designed for a different purpose. Ask your printer whether you should save your file in a PDF/X format.