Image Functions

(1)Pre-filter

[A.4.7 SET WINDOW command / DTC mode]

The pre-filter performs filtering before processing the Dynamic Threshold. Ordinary and Ball- point Pen are selectable in Pre-filter.

Table 3.7 Parameter of Pre-filter

Name of

value

Effect with IPC-2D

Effect with IPC-3D

Default

parameter

 

 

 

 

 

 

 

 

 

Ordinary

X’00’

Linear gamma curve

Linear gamma curve

 

 

 

 

 

X’00’

High Contrast

X’10’

Makes low contrast

 

 

 

Image clear (for dark

 

 

 

 

background document)

 

 

 

 

 

 

 

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.

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