Choosing the Right PDF Preset
High Quality Print: Use this preset to create a PDF document for high-quality printing on desktop printers and proofers. Color and grayscale images are downsampled to 300 ppi. Colors are left unchanged (they aren’t converted to another color space). Transparency is retained (Acrobat 5 compatibility is the default).
Press Quality: Use this PDF preset for high-quality commercial printing where the printer is comfortable receiving a PDF with live transparency. Acrobat 5 compatibility is selected, and transparency isn’t flattened. Color and grayscale images are downsampled to 300 ppi (considered an industry standard for commercial printing). RGB images are converted to CMYK; CMYK values are unchanged. This would be a good choice if your printer is sending this to an imagesetter or platesetter out of Acrobat 7 Professional. Acrobat can handle live transparency and produce high-quality separations.
The next two presets follow PDF/X standards: To reduce printing errors and enable the successful exchange of files, Adobe worked with other vendors and professional users to develop the PDF/X standards?a family of ISO standards which are a subset of PDF designed for print workflows. Many printers are encouraging their customers to use PDF/X. They’re also a good choice if you’re not sure what your printer wants.
PDF/X-1a:2001: Both of the PDF/X presets in InDesign set Acrobat 4 compatibility which flattens transparency. (Therefore, if you choose either of these choices, be sure to visit the Advanced panel and select the High Resolution Transparency Flattener Preset to retain the quality of your type and vectors.) PDF/X-1a supports CMYK and spot colors but doesn’t allow color management. RGB images are converted to CMYK; CMYK values are preserved. Image resolution settings are the same as the Press Quality preset.
PDF/X-3:2002: This PDF/X preset is similar to PDF/X-1a except that it also supports embedded RGB profiles and color management. This standard is more widely used in Europe than in North America. Choose this option for color-managed environments where you expect the printer to optimize color reproduction for the specific printing environment.
Smallest File Size: Use this preset for onscreen display, email, or the web. Color images are downsampled to 100 ppi, grayscale images to 150 ppi. Transparency is retained (Acrobat 5 compatibility is the default).