Independent Dot Erase - Gestetner B003 Service Manual

IMAGE PROCESSING

Independent dot erase

By default, this process is used only in text mode and generation mode to erase
independent black dots appearing in the copy or reduce their image density.
However, it can be enabled for other modes with the following SP modes.
SP4903 60
62
63
64
The machine compares each pixel (refer to the diagram below) with the pixels
around the edges of the surrounding 3 x 5 area. If the sum of the pixels at the
edges is smaller than the threshold value stored in the SP, the object pixel is
changed to 0 (white) or reduced in density to an average of the pixels around the
edge, depending on the SP mode setting. Each SP mode has 16 levels as follows.
A= Sum of the pixels at the edges
SP mode
value
0 Disabled
1 If A < 16, the pixel is deleted
2 If A < 32, the pixel is deleted
3 If A < 48, the pixel is deleted
4 If A < 64, the pixel is deleted
5 If A < 80, the pixel is deleted
6 If A < 96, the pixel is deleted
7 If A < 128, the pixel is deleted
Pixel density reduction works as follows. For the example in the
following drawing, when the SP mode value is "11", the sum of the
pixels around the edge is less than 48, the object pixel value is
reduced from "90" to "3" as shown below.
A: (0 + 0 + 30 + 7 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0) / 12 = 3
B003/B004/B06/B007
Independent Dot Erase Level (Text)
Independent Dot Erase Level (Text/Photo)
Independent Dot Erase Level (Pale)
Independent Dot Erase Level (Generation)
Function
SP mode
value
8 Disabled
9 If A < 16, density is reduced
10 If A < 32, density is reduced
11 If A < 48, density is reduced
12 If A < 64, density is reduced
13 If A < 80, density is reduced
14 If A < 96, density is reduced
15 If A < 128, density is reduced
6-28
Function
0 0 3 0
0 7
0 9 0 0
0 0
0 0 0
B004D503.WMF
SM