2-14-(22)
Density Defects
Section 2-14
1.
The density distribution of the whole measurement region is calculated.
2.
The density difference between the lowest and highest density value be-
comes 100%.
3.
The point where the edge level density change is detected becomes the
edge.
Noise Level
Set a noise level between 0 and 255 to assist the determination of edges. The
maximum density and minimum density within the edge detection area is cal-
culated and if the difference between the two values is less than the noise
level, then the Controller determines that there is no edge. Normally the
default setting of 20 is sufficient. Adjust this to a higher value, however, if noise
is causing false edges to be detected.
(Within the edge detection region)
Max. density - min. density < noise level
no edge
NG measurement
result
Max. density - min. density
noise level
Edge
Used for measurement
Example: When noise level is set to 30
Noise Width
Set the noise width between 0 and 255 to evaluate noise.
If the density distribution from the position where the edge was first detected
falls to below the edge level within the noise width range, the detected point is
judged as noise. Normally the default noise width setting of 0 is sufficient. If
noise is causing incorrect detection, make this value higher.
Maximum density value
Edge level
Minimum density value
100%
50%
0%
Measurement region
Max. density 60
Min. density 15
Edge
detection
region
Edge
detection
region
25 10 30
Processed as no edge detected.
Measurement result: NG
60 15 30
Edge detected so
measurement performed
Max. density 25
Min. density 10
