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IMAGE PROCESSING
(2) ACC Test Pattern
The IPU board firmware has a test pattern that has eight 17-step gradation scales
for each color (KCMY), including background white, for Text and Photo modes.
(3) ACC (Auto Color Calibration)
This machine automatically calibrates the printer gamma curve when the user
selects ACC.
When ACC is activated, the machine prints out an ACC Test Pattern. The user puts
the test pattern on the exposure glass, then the machine scans the test pattern.
The machine scans eight lines, one for each color (KCMY) in text mode, and one
for each color in photo mode.
The machine corrects the printer gamma by comparing the ideal settings with the
current image density. Then the machine combines the corrected gamma curve
with the High, Middle, and Low ID values currently in memory (these are not reset
to the defaults first, as in some earlier models).
The machine the calculates the ID max (amplitude of the gamma curve) based on
data from the ACC scan.
The corrected printer gamma curves can be adjusted further using SP mode, as
discussed on the previous page (see Replacement and Adjustment, Copy Image
Adjustment).
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A259X010.WMF
24 February, 1999
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