Adobe ACROBAT 3D Manual page 622

Viewing color warnings
Output problems can occur when a document's colors are not reproducible on a particular
press, or rich black is used unintentionally on type. To diagnose such color problems
before handing off an Adobe PDF document for high-end output, you can use the various
color warnings in the Output Preview dialog box. Pixels in areas that trigger the warning
are displayed in the warning color, which is identified by the swatch color next to the
warning type. You can change the warning colors using the swatch's color picker.
Previewing color warnings on your monitor lets you check the following:
Show Overprinting indicates how blending, transparency, and overprinting will appear in
color-separated output. You can also see overprinting effects when you output to a
composite printing device, if you select Simulate Overprinting in the Output panel of the
Advanced Print Setup dialog box. This is useful for proofing color separations.
Rich Black indicates areas that will print as rich black--process black (K) ink mixed with
color inks for increased opacity and richer color. Rich-black objects knock out the colors
beneath, preventing background objects from showing through. This is usually desirable
only for large, black display type.
Output Preview dialog box configured for viewing color warnings
To view color warnings:
1. In the Output Preview dialog box, select the profile from the Simulation Profile pop-up
menu that describes the target output device.
2. Choose Color Warnings from the Preview pop-up menu.
3. Select Show Overprinting, or Rich Black to highlight color problems in the open PDF
page.