57
4-13 ITEM Overview (Defect)
Item Overview
Another setting
Note
Guidelines for setting detection size and detection interval
• Detection size
Determine the detection size roughly according to the size of the defect to
be detected.
Setting a smaller detection size results in stronger detection sensitivity,
while setting a larger detection size results in weaker detection sensitivity.
When a larger detection size is set, the difference with elements that are
not defects decreases as the density of elements other than defects also
is included in the calculation at (2). In other words, the more background
that is included in the detection area, the weaker the detection sensitivity
becomes.
• Detection interval
Determine the detection interval roughly according to the size of the
defect and the detection size.
The larger the detection interval that is set, the shorter the processing time
becomes.
When the detection area is greater than the defect, set a smaller detection
interval.
When the defect is greater than the detection area, set a slightly larger de-
tection interval.
When a small detection interval is set, elements overlapping the edge of
the defect also are included in the comparison, and so the defect value de-
creases, which results in less stable detection of the defect.
Detection size 4 to 64 (default value: 8)
4 to 64 (default value: 8)
Small detection areas corresponding to the detection size are cre-
ated and the distance between each area is defined by the detection
interval.The average density of each detection area is calculated, and
then is compared with the surrounding average density.
Noise level
0 to 255 (default value: 60)
Set the level to be judged as noise. A defects whose defect value is
lower than the noise level is removed as a noise.
Set a higher value when noise is detected as a defect, or set a lower
value when the defect cannot be detected.
Detection interval
Detection area corresponding
to detection size.
(1)
(2)
Detection size
Defect
Sensivity
Proecessing time
Stronger
Longer
Weaker
Shorter
Z01E-EN-01+ZFX+SettingGuide.book Seite 57 Mittwoch, 13. Februar 2008 2:38 14
