Image Processing; A/D Conversion - Ricoh C217 Service Manual

8. IMAGE PROCESSING

Image processing resolves how to transform an optical image of a
continuous line, made up of an infinite number of color shades, into 2592
lined-up dots (pixels), each of which is black or white.
There are two basic sub-processes: first A/D conversion, i.e. converting an
analog image to 4-bit digital data representing 16 shades of gray; second
binary processing, i.e. transforming that digital data into black or white pixels.

8.1 A/D CONVERSION

(1) (2)
OS
Inversion &
CCD
DOS
Amplification
(6)
This block diagram shows the A/D conversion process (A/D= Analog to
Digital). The analog signal generated from the CCD is inverted and
amplified. Then the analog signal is converted into a 4-bit digital signal and is
sent to the binary processing circuit.
The following sections (8.1.1 - 8.1.8) will give a brief explanation of the
various steps in the A/D conversion process.
C217
Shading
Distortin
Correction
(3)
VS
A/D Conversion
Parameter
Setting
Image mode/Image density
Setting
2-38
(4)
VPH
Peak
Hold
(5)
Black
VB
Level
VH
M1
A/D
M2
Converter
M3
VL
(7)
(8)
Shading
Distortion
Memory
to
4-bit Digital Data
Binary processing
Circuit
SM