How do I view overprints and separations in a PDF?
Use the setting called "Overprint Preview": This setting specifies whether Overprint Preview mode is on only for PDF/X files, never on, always on, or set automatically. When set to Automatic, if a document contains overprints, then Overprint Preview mode is activated.
The Overprint Preview mode lets you see (onscreen) the effects of ink aliasing in the printed output. For example, a printer or service provider could create an ink alias if a document contains two similar spot colors and only one is required. The Overprint Preview mode also l simulates all the overprint of elements that may be happening in the file just like it would on press production.
We suggest changing this setting to be "Always or Always On", so you will always see the elements that overprint for production environments.
Another way is using the Output Preview tool. The great thing about this tool is the ability to view the actual separations in the PDF. This gives you the ability to turn separations on and off as needed to check the file.
The Output Preview window provides the tools and controls to help you simulate how your PDF looks in different conditions. The top part of the dialog box has several controls for previewing your document, including "Simulate Overprinting".
The Preview menu allows you to switch between previewing separations and previewing color warnings. When you select Separations, the bottom half of the dialog box lists information about the inks in the file, as well as total area coverage controls. When you select Color Warnings, a warnings section replaces the separations section and provides information about ink warning controls. The preview settings you specify in the Output Preview dialog box are reflected directly in the open document.