Image Processing; Scanner Section Image Processing Block Diagram - Develop QC 2235 Plus Service Manual

QC 2235plus Theory of Operation Ver.1.0 Mar. 2004

19. Image processing

19.1 Scanner section image processing block diagram

1. Photoelectric conversion
2. Analog-to-digital conversion
3. Shading correction
4. Line-to-line variation correction
5. Zoom/movement processing
7. Image data editing
8. AE processing
To the MFP Control Board
• The following detail the image processing operations performed by the Scanner Section.
1. A reduction type CCD Sensor is used to read the light reflected off the original and con-
vert the optical data to a corresponding electric signal. To make data processing faster,
data transfer and output are done through two channels, one for even-numbered pixels
and the other for odd-numbered pixels.
2. The odd and even analog signals output from the CCD Sensor chips are synthesized to
form a single string of signal data which is in turn converted to 8-bit digital signals (256
gradation levels).
3. A correction is made of errors that occur due to variations in sensitivity of each CCD
chip and the light distribution varying along the length of the Exposure Lamp. The shad-
ing correction is made by holding the peak value, i.e., the maximum value of readings
taken of multiple lines, to prevent adverse effects on the image due to dust on the shad-
ing sheet.
4. Memory called FIFO is employed to compensate for a deviation in the scanning posi-
tion of the original, which represents a gap between two adjacent CCD chips, thereby
matching the output timing of R, G, and B data. Also, the color aberration of the Lens is
compensated at this time.
5. FIFO memories are used to enlarge or reduce the image. The image is enlarged by
increasing the number of data readings and reduced by decreasing the number of data
readings.
CCD Sensor Board
Image Processing Board
6. ACS processing
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Image processing