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IMAGE PROCESSING
Image Separation
The original image is classified into the text and photo (dot screen) areas.
Edge Separation
• Used to locate text and line diagrams
• Locates areas of strong contrast.
• Looks for continuity of black or colored pixels.
• Looks for continuity of white pixels around black or colored pixels.
• Only uses data from the green CCD.
Dot Screen Separation
• If white pixels are not detected around non-white pixels, it is a dot screen area.
Colored Text Separation
• Identifies whether the text area's pixels are black or color.
• Based on:
1) Differences among the RGB maximum signal levels.
2) Output levels of the RGB video signals.
ACS (Auto Color Selection)
R
RGB signal after scanner γ correction
B156D017.WMF
The auto color selection function determines if an original is black/white or color.
Black copy mode or full color mode is automatically selected.
Selection is made based on the difference between the RGB signal levels.
RGB video signals are compared.
If the maximum difference among RGB signals is within a certain range, the
original is considered black and white.
G
B
Black and white first
255
0
102 128
(40% UCR rate)
(50% UCR rate)
6-28
10 February 2005
204 (50% UCR rate)
153 (50% UCR rate)
Color first
RGB common data
255
B156D018.WMF
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