Ricoh PRIPORT VT 2000 Series Service Manual page 57

(Corrected Waveform X 80%)
28 February '91
Peak Hold of Background
VPH
VH (Corrected
Waveform x 80%)
VL (VPH x 6%)
(Black Level)
VT2100/2130/2150: 1.7V
VT2300/2500: 1.4V (Black Level)
b). Photo Mode -- (Selector 2 Switch 2 ON)
The V of the A/D converter is set to 80% of the potential difference
H
between 1.7 volts (VT2300/2500: 1.4 volts) and the output from the D/A
converter (converted shading distortion data). This corrects for shading
distortion as well as matching the output level to the original back-
ground because the reference level of the D/A converter is set to the
original peak hold level.
Also, V is set to 6% of the potential difference between 1.7 volts
L
(VT2300/2500: 1.4 volts) and the peak hold level of the original.
2-30