Gamma Correction (Printer Gamma) - Ricoh A66 Service Manual

IMAGE PROCESSING

4.5.6 Gamma Correction (Printer Gamma)

Fig. 2
Fig. 1
(1) BKCMY Gamma
Ideally, the gamma curves for Yellow, Magenta, Cyan, and Black should be
identical, as shown in figure 1. However, they are not, because electrical
components always vary slightly, resulting in varying gamma curves, as
shown in figure 2.
To compensate for this discrepancy, the Auto Color Calibration (ACC)
procedure can be done if color reproduction is becoming unsatisfactory.
ACC creates new gamma curves for each color in each mode (letter, photo,
Bk letter, glossy photo). After ACC, the gamma curve for each color mode
can be adjusted with service programs (see Replacement and Adjustment,
section 6-4, Image Processing)
Using these programs, each gamma curve can be adjusted using 4 different
modes: ID max., High ID, Middle ID, and Low ID, as shown on the following
page. If the previous gamma curve was better, it can be recalled. Also, the
factory settings can be loaded using SP 5-610-4.
A166/A187/A189 2-58 SM