Video Control Unit (Vcu); Printer Gamma Correction - Ricoh B121 Service Manual

6.5.4 VIDEO CONTROL UNIT (VCU)

Fine Character and Image (FCI)
The FCI performs image smoothing. This functions only affects binary picture
processed images for certain original modes.
Fig. A
Fig. B
Fig. C
Usually, binary picture processing generates jagged edges on characters, as
shown in the above illustration. These are reduced using edge smoothing. The FCI
changes the laser pulse duration and position for certain pixels.
Fig. A shows the four possible pulse durations, and Fig. B shows how the laser
pulse can be in one of three positions within the pixel. Fig. C shows an example of
how edge smoothing is used.
FCI smoothing is only effective when Text 2 or Special 1 is selected. There is no
SP adjustment for this.

Printer Gamma Correction

Printer correction corrects the data output from the IPU to the laser diode to
account for the characteristics of the engine components (e.g. drum, laser diode,
lenses).
The machine chooses the most suitable gamma curve for the original type selected
by the user. There is no SP adjustment for this.
B121/B122/B123
4/4
Sub Scan
Direction
Main Scan Direction
3/4 2/4 1/4
6-28
IMAGE PROCESSING
0
B121D933.WMF
SM