Adobe Acrobat's Portable Document Format, or PDF, allows you to create documents designed to display on computers, as well as print on printing presses. However, computers produce color for display on computer monitors by combining shades of red, green and blue -- the RGB color model. Printing presses, on the other hand, use the cyan, magenta, yellow, and black, or CMYK, color model. In order to get PDFs to print properly on printing presses, it's often necessary to convert them from RGB to CMYK. You can convert RGB PDFs to CMYK from the Preferences dialog box in Adobe Acrobat Pro.
Open the PDF you want to convert to CMYK in Adobe Acrobat Pro by selecting the "File" menu and choosing "Open." This displays the Open dialog box. Navigate to the file, select it, and then click the "Open" button.
Click the "Edit" menu and choose "Preferences." This opens the Preferences dialog box.
Click "Color Management" in the Categories list.
Click the "Settings" drop-down menu and choose "North America Prepress 2." This tells Acrobat to preserve the document's CMYK values for a North American printing press.
Note that many print shops contract out large CMYK print runs to printing companies all over the world. Acrobat Pro also has European and Asian prepress profiles. Ask your print shop which option to choose.
Click the "CMYK" drop-down menu and choose the appropriate setting for your print shop's printing press. Ask your print shop which option to choose.
Click the "File" menu and choose "Save As." Name and save the file.
For example, if the document originated in Adobe InDesign, a popular print-document layout program, you can use that program's Press Quality PDF preset. Click the "File" menu, choose "Adobe PDF Presets," and then select "[Press Quality]." This creates a PDF optimized for a CMYK printing press.