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IPC-3D:
Dynamic Threshold is identical to the Simplified Dynamic Threshold in IPC mode.
(See section 3.3.2)
NOTICE 1: Threshold, Brightness, and Contrast settings are ignored in DTC mode.
NOTICE 2: Gamma correction is also ignored in DTC mode.
(1)
Pre-filter
The pre-filter performs filtering before processing the Dynamic Threshold. Ordinary and Ball-
point Pen are selectable in Pre-filter.
Name of
Control
parameter
register No
Ordinary
A#3/B#3
High
Contrast
Use Ordinary basically. For the texts written by ball-point pens, use of Ball-point Pen may better
for OCR. This is because, the texts written by ball-point pens actually have two thin lines per
stroke. To human eye, this is not big problem, but OCR may not recognize the text. The Ball-point
Pen filter detects lighter areas compared to the surroundings and increases the density of the
lighter area. puts these two lines into one solid line. This can prevents cuts, void or too thin lines.
Table 3.9 Parameter of Pre-filter
Value
Effect with IPC-2D
B'1xxxxxxx'
Linear gamma curve
Makes low contrast
Image clear (for dark
B'0xxxxxxx'
background
document)
3.3 Optional image function
Effect with IPC-3D
Linear gamma curve
Default
Ordinary
3-13
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