15 February 2006 SCANNING
6-29
Detailed
Descriptions
6.5.4 SCANNING MAGNIFICATION
Book Mode
Reduction and enlargement is done differently for main scan and sub scan:
• Main scan: Handled by image processing in the IPU.
• Sub scan: Handled by varying the speed of the scanner motor.
Reproduction ratios of 50% or higher: The scanner speed is lower for higher
magnification ratios. For example, for 200% enlargement, the scanner motor speed
is reduced to 50%.
Reproduction ratios of less than 50%: The scanner motor cannot run fast
enough. So, the scanner slows to half the speed required for that reduction ratio.
For a 49% magnification ratio, the scanner speed is the same as for 98%
magnification. This causes twice as many scan lines as needed, so alternate lines
are removed.
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