How Calibration Works - Xerox Digital copier printers User Manual

6
6-2 Color Calibration

How calibration works

Success in obtaining satisfactory print quality from a digital color printer depends on
many factors. Among the most important are establishing and maintaining optimal
toner densities. Density is a measure of the light absorbed by a surface. The saturation
of toner colors, which affects output densities from your copier, is affected by such
variables as room humidity and service settings, and also tends to drift over time.
Regular calibration corrects for day-to-day variations in densities.
Calibration works by creating calibration curves on your Fiery SI server that
compensate for deviations from desired density values. These calibration curves are
generated by creating a measurements file—a file containing numerical values
corresponding to the amount of toner being printed for the full range of colors—and
comparing it to a target.
Measurements
Measurements files provide numerical values that correspond to your copier's toner
density for each color. To create a measurements file, you can scan a page from your
copier and use AutoCal, connect an X-Rite DTP32 densitometer to the Fiery SI and
record values, or connect an X-Rite DTP32 densitometer to your Macintosh
computer's modem port or your IBM-PC compatible's serial port and measure values
with the Fiery XJ Print Calibrator. You may also be able to connect any Status T
densitometer to your Macintosh or IBM-PC if you have utility software provided by
the densitometer manufacturer to create a measurements file.
Targets
Target files define desired calibration results. Several target files are provided with the
Fiery SI, and you can create additional ones as needed by modifying existing targets.
When you calibrate the Fiery SI, you can select the target file that corresponds to the
type of printing you are doing.
The targets provided with the Fiery SI are:
• 5760/65 or 5790—Optimized for best results for specific copier performance. You
should use the copier target if you are going to use the copier's ICC profile to print
CMYK data or the Color Rendering Dictionaries (CRD). The CRDs are used if you
print an RGB file from Photoshop, or if you use a PostScript Level 2 Printer Driver
(Adobe PostScript Printer Driver for Macintosh, Adobe PostScript Printer Driver for
Windows, or Apple LaserWriter Printer Driver version 8.0 or later).