Konica Minolta bizhub C658 Service Manual page 1914

bizhub C658/C558/C458/C368/C308/C258
18.2 Write section image processing block diagram
18.2.1 Processing flow
From scanner section
1. Shading correction
(only image data from scanner
section)
2. RGB gap correction/
color aberration correction
DSC board
3. Detection of security pattern
4. ACS control/5. AE processing
6. Free erase
7. Image data editing
8. Image area discrimination
9. Miscellaneous processing
(improved reproduction of
black text, edge emphasis,
smoothing and color balance)
10. BTC compression
11. Input buffer memory
12. JBIG compression
13. File (code) memory
DRAM:2GB (standard)
HDD:250GB (standard)
14. JBIG expansion
15. Memory access coordinator
18.2.2 Detail
The following detail the image processing operations performed by MFP board on the Write section.
1. Correct variations in reading caused by pixel-to-pixel variations in sensitivity of the CCD sensor and uneven light distribution by the
exposure LED. A peak-hold-type shading correction is performed, in which the maximum value of two or more readings of two or more lines
is taken to prevent effect due to dust or dirt on the shading sheet. (only image data from scanner section)
2. To correct differences in the position of each chip of CCD sensors R, G, and B, FIFO memory is adopted to match the output timing. Also
correct color aberration of the lens.
3. The security pattern created during printing on this machine is detected and copying is enabled or disabled through a password. (when
security kit SC-508 is mounted)
4. The scanning area is divided into multiple blocks. The ratio of color or monochrome is calculated for each of these blocks. The machine
then determines whether the entire original is colored or monochrome.
5. A histogram of lightness for AE processing is generated. The AE level of the document is determined based on this histogram and AE
processing is performed.
6. If outer document elimination is selected from the control panel, document area determination processing is performed for each line within
the document area data acquired during prescan. Then, the START and END positions of the document area in the main scanning
direction are detected and the area outside the START and END positions is erased as the outside-the-document area.
7. R, G, and B data are then converted to value and color component data for adjustments of saturation, lightness, and hue.
8. Each image area, whether it is a color edge area, black edge area, dot area, or a continuous gradation area, is discriminated.
9. Other types of processing performed are the improved reproduction of black text, edge emphasis, smoothing and color balance.
10. Each image data of R, G, and B is compressed to reduce the consumption of data capacity.
O THEORY OF OPERATION bizhub C658/C558/C458/C368/C308/C258 > 18. IMAGE
MFP board
16. Frame memory
17. Output buffer memory
18. BTC expansion
19. Magnification processing
in the main scanning
direction/movement
processing
20. Magnification processing
in the sub scanning
direction
21. Color conversion
processing
RGB to YMCK
Photo mode only
22. Embedment of security
pattern
23. Area discrimination FEET
24. Interpolation
25. Gamma correction
26. Error diffusion (binary)
27. Screening
28. Resolution change
29. Delay control between
drums
30. Main scanning position
correction
Speed conversion
Modulation
To PH unit
O-139
PROCESSING