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Quality tab in the Job Parameters window
Parameter
Trapping
Overprint
Screening
Option
Enable Trapping
Black overprint
PostScript overprint
Dot 150
Description
Applies trapping to your job.
Trapping is a solution that solves misregistration between
color separations in both offset and digital printing. This
occurs no matter the accuracy of the printing device, and
results in white lines around objects on top of a background
(in a knock-out procedure) and also between adjacent colors.
Note: If you don't select this option, it does not affect
trapping incorporated by DTP applications—for example,
Photoshop. FAF should not be used with application-based
trapping. In a PostScript file that already contains trapping
from the originating application, it is not necessary to use
CX print server trapping.
Frame thickness: The desired value for the thickness of
the trapping frame. The thicker the frame, the less chance
that white areas appear between images.
Protect small text: Text that is smaller or equal to 12 pt. is
protected and not framed when the trapping algorithm is
applied. You can use this option for small or complex
images, since thicker frames can decrease quality by hiding
parts of an image.
Ensures that black text prints cleanly within a tint or picture
area. The text appears in a richer, deeper black, with the
underlying CMY values equal to those of the printed
background.
Uses the overprint information that exists in the PostScript
file. This parameter also determines whether the DTP
application PostScript overprint settings are honored in the
RIP.
Screening converts CT (Continuous Tone) and LW (Line
Work) images into information (halftone dots) that can be
printed. The human eye "smooths out" this information,
which seems visually consistent with the original picture.
Thus, the more lines per inch, the more natural the image
appears. Screening is achieved by printing dots in
numerous shapes or lines in an evenly spaced pattern. The
distance between the screen dots or lines is fixed and
determines the quality of the image. Printers can work with
even amounts of toner and still produce a wide range of
colors when you use screening. The darker the color, the
larger the dot.
In order to print an image on a digital printer or press the
color server needs to digitally approximate the grayscale
values with different distributions of black and white pixels.
This process is commonly referred to as half-toning. Digital
halftoning begins by sampling the original image at the
printer dpi and constructing digital halftone cells.
Applies a low dot-type screen. The screen of each
separation is printed at a different angle.
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