Theory of Operation Ver. 1.0 Sep. 2008
21. Image processing
105
bizhub C200
Composition/Operation
• The following detail the image processing operations performed by MFBU board on the
Write section.
1.
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 shading 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 shading sheet.
2.
Memory called FIFO is employed to compensate for a deviation in the scanning
position of the original, which represents a gap between two adjacent CCD chips,
thereby matching the output timing of R, G, and B data.
3.
Makes the necessary corrections so that the printed gradations have linear charac-
teristics, since the image density of the input image data is not directly proportional
to that of the printed image because of the changing developing and PC drum char-
acteristics.
4.
The R, G, and B data are translated to corresponding Y, M, C, and K density data.
5.
A background adjustment of the image data is made according to the settings
made on the control panel and other controls.
6.
The image data is enlarged or reduced according to the settings made on the con-
trol panel and other controls.
7.
A sharpness adjustment of the image data is made according to the settings made
on the control panel and other controls.
8.
A contrast adjustment of the image data is made according to the settings made on
the control panel and other controls.
9.
A brightness adjustment of the image data is made according to the settings made
on the control panel and other controls.
10. A saturation adjustment of the image data is made according to the settings made
on the control panel and other controls.
11. The Y, M, C, and K data are translated to corresponding R, G, and B density data.
12. This converts RGB 24-bit image data to 8-bit gray scale data, converts to 2-value
data by error diffusion processing, and outputs the data.
13. This performs sub-sampling processing of YMCK data, performs raster/block con-
version, and outputs the data.
Y109670-2 Theory of Operation