Printer Gamma Correction - Ricoh B202 Service Manual

IMAGE PROCESSING

Printer Gamma Correction

High
Output ID
Low
Low
B178D611.WMF
The gamma curves for yellow, magenta, cyan, and black should be identical, as
shown in figure 1. However, slight variations in the electrical components can result
in varying gamma curves, as shown in figure 2.
• Printer characteristics are much more variable than scanner ones. Printer
gamma needs recalibration and adjustment from time to time.
• The Auto Color Calibration (ACC) procedure compensates for any discrepancies
in color reproduction.
• ACC makes new gamma curves for each color in each mode (text, photo, and
black text).
• After ACC, you can adjust the gamma curve for each color with service program
(SP4-918).
• 4 different modes:
1) ID max.
2) Shadow (High ID)
3) Middle (Middle ID)
4) Highlight (Low ID)
• You can get back the previous gamma curve if it was better.
• You can load factory settings with SP 5-610-4.
NOTE: If the factory settings have been overwritten, this will return the new
values, not the actual settings made in the factory. This is deliberate,
since some drift is expected. After a time, the original factory settings
may no longer be suitable.
• Factory settings can be overwritten by the current gamma settings with SP5-610-
5.
B202/B178/B180
Example: Y
Input Signal High
Fig. 1
6-34
K
Fig. 2
B178D522.WMF
SM