Ricoh JP3000, Service Manual, Page: 77 / 693

IMAGE-PROCESSING
2-13
SM C231/C237/C238
Det
a
iled
Sect
io
n
De
s
c
ri
ptions
2.2.3 BINARY PROCESSING
In the halftone-processing chip, the 6-bit digital signal data is generated in the A/D
conversion circuit and is sent to the binary processing circuit. At that time the data
is inverted to match the binary processing circuit. Therefore, the white peak level
becomes 0, and the black level becomes 63.
In the binary processing circuit, the 6-bit data is converted into 1-bit data for black
or white pixels. The binary processing for the letter and photo is different, as
follows:
Letter Mode, Letter areas in Letter/Photo Mode: MTF (Modulation Transfer
Function) Correction
Photo Mode, Photo areas in Letter/Photo Mode: Error Diffusion Processing
Data Compensation Processing
In this process, the 6-bit data are converted based on a compensation curve
(gamma curve) which corresponds to selected image settings. For example, if a
darker image is selected, a compensation curve, which converts each pixel value
to a higher number, is selected. The output data is still 6-bit.
D a t a
C o m p e n s a t i o n
Circuit
6-bit data from
the A/D conversion
P C B
G a m m a c u r v e
selection signal
6-bit data
Input
Output
C231D514.WMF
C231D515.WMF