Binary Processing; Data Compensation Processing - Ricoh C231 Service Manual

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.
Input
6-bit data from
the A/D conversion
P C B
G a m m a c u r v e
selection signal
SM
Output
Data
Compensation 6-bit data
Circuit
C231D514.WMF
2-13
IMAGE-PROCESSING
C231D515.WMF
C231