Xerox DocuColor 250 Online Help Manual page 78

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completely random positioning does not work well. The
stochastic screen prevents screening interference
patterns, but it can cause graininess and other visual
artifacts. Therefore, stochastic screening as
implemented by your Xerox color printer uses a
complex algorithm to determine the optimum
placement of dots in order to appear random while
reducing graininess. This "random" arrangement of
dots means there is no "direction" to the screen; and
therefore no screen angle exists. The variable spacing
of the dots means there is no fixed spacing, and
therefore there is no screen frequency. So, without
frequency or angle, there is no possibility of moire
between the four process-color screens, or even of
moire from patterns within an image.
Setting the Halftone Screen
To set the halftone screen within Job Manager, complete the
following steps:
1. Open the Job Manager.
2. Double-click a job in the Active or Inactive Jobs list. You can
access Completed jobs if Retain PDL Files is enabled. For
additional information about Retain PDL Files see Setting the
Job Policy.
3. Select the Image Quality Tab.
4. Select the Halftone FAB.
5. From the Halftone menu, select the desired setting according
to your system. For most jobs, you will want to accept the
default, "System Specified" setting.
6. If desired, enter a Stroke Thickening value. Stroke Thickening
is available for PostScript, TIFF, PCL, and PDF formats. Adjust
the Stroke Thickening to control the thickness of fine lines
created by the PostScript stroke command. The available
range is located below the spin box.
7. Select [OK] to accept the changes and exit the job properties
tabset, or [Apply] to commit changes without exiting the dialog.
If you do not wish to retain your changes, select [Cancel] to
exit without saving changes.
Setting Image Resample, or Interpolation, options
DocuSP provides the user with the ability to select an
interpolation, or image resample, method in order to achieve
maximum Image Quality at the desired RIP performance.
Interpolation is defined as the process of estimating a value of a
function between two known values. In the Image Interpolation
context, the function of known values is the input image, and the
estimated values are the values calculated for the output image.
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