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Image Functions
(2)
Gradation
Gradation specifies the gamma curve correction before processing Dynamic Threshold. When
scanning news papers or old documents which background is dark, it is desirable that the gamma
curve has coarse steps in the lighter side and fine steps in the darker side. This is called High
Contrast gamma curve.
As the Dynamic Threshold with IPC-3D includes an automatic contrast adjustment, High Contrast
setting is not required.
Control
Parameter
register
No
Ordinary
A#3/B#3
High
Contrast
* For dark background document such as newspaper or old document
3-14
γ curve
Table 3.10 Parameter of Gradation
Value
Effect with IPC-2D
Normal gamma curve
X'xxx00xxx'
(for general document)
Makes low contrast
X'xxx10xxx'
Image clear
Effect with IPC-3D
Normal gamma curve
No effect
Default
Ordinary
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