System information

• Common pitfalls of overprint behavior on page 213
Color spaces
A PDF document can contain objects of different color spaces: Separation, DeviceN, CMYK, Gray,
calibrated Gray or RGB, Lab or ICC-based colors. The color space of the object has an impact on
the object’s overprint behavior. The following rules apply here:
RuleOverprint
mode
Object typeColor space
Only those inks are specified as listed in the
respective color space.
IrrelevantIrrelevantSeparation
DeviceN
Separation Black, for example, will only have the
black ink specified, not cyan, magenta or yellow.
Cyan, magenta, yellow and black inks are
specified. To determine the percentage of the
IrrelevantIrrelevantGray
RGB
inks in non-CMYK objects, the colors in these
Lab
objects are converted to CMYK according to the
normal color conversion rules.
ICC-based colors
An object in Gray, for example, may have the
following inks specified:
Calibrated Gray or
RGB
C: 0 %
IrrelevantImage
Shading
CMYK
M: 0 %
Y: 0 %
Standard
(OPM 0)
Text
Line art
K: 60 %
Consequently, objects in Gray will always knock
out the underlying cyan, magenta or yellow,
regardless of the object type or overprint mode.
Image
masks
Only those inks are specified of which the tint
value is not equal to zero.
Illustrator
(OPM 1)
We learn the following from this overview:
• Only CMYK text, line art and image masks have an overprint behavior which depends on the
overprint mode (OPM 0 or OPM 1).
• There is black and there is black. Objects in a spot color named “Black”, in the Gray color space,
or in the “Black” ink that is used to render the K plate of CMYK have the same overprint behavior,
and the overprint mode (OPM 0 or OPM 1) makes a difference for CMYK Black. Objects in
Separation Black or in Gray, however, will overprint differently.
Object in Separation BlackObject in spot color black, Gray or 100 % KInk
0 %Cyan
0 %Magenta
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