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980541-001 Rev. A P640i Card Printer User Guide 49
Color Calibration
Start > Printers (or Printers and Faxes) > Right click
Zebra P640i > Properties > Device Settings > Color
Calibration
Color rendering in the P640i can be described in terms
of a curve, which determines how much power is put
into the printhead for a given shade. The Y, M and C
“color curves” can be separately modified by the Gain
and Offset parameters shown here.
Note: Typically,
the set of values should be the same for each color.
Click Restore Defaults
if you are not satisfied with
adjustments made.
Offset: Shifts the color curve up (darker) and down
(lighter).
Gain: Adjusts steepness of the curve. Lighter shades
will remain unchanged, but darker shades will get
darker or lighter as the number is increased or
decreased.
Prehea : Adjusts how much the head is preheated
before each print line (every three hundredths of an
inch). A larger value darkens (sharpens) the leading
edges of colored areas. A lower value may result in
“feathering” - starting light, then darkening over the
following few pixels as the head heats up.
Black Panel Density, Black Panel Preheat: See
K (Black) Panel Printing, above.
Contrast Adjust: A subtle color printing control,
allows the user to shape the printer’s “lightness curve”
(roughly speaking the “
L” in the color space called
L*a*b*). In practical terms this means the ability to
control how the P640i resolves, or differentiates, the
lighter and darker shades. Between contrast settings of
0 and 100, the lightness curve transitions from linear
to sinusoidal. Linear (0%) tends to result in a low
contrast, muddy looking image. Sinusoidal (100%)
gives mostly good results, but tends to sacrifice the
lightest and darkest shades. For most purposes, select
50% and leave it there.
Head lowered: Print head bracket activates
sensor. Motor continues to drive a few
more steps (see Printhead Position
Adjust), compressing the spring to deliver
Motor
shaft
Print-
head
Quadrant
Printhead spring
Head raised : Print head bracket clear of
sensor, arrowed. The quadrant is driven by
a pinion on the print head stepper motor
shaft.