Omron F250-UME Software Manual page 184

Edge Position Compensation
Edge Level
Noise Level
2-7-(8)
Set a density change level between 0 and 100 that will indicate the edge. Nor-
mally, the default setting of 50% will be fine.
The edge is normally detected as follows:
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.
Measurement region
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
result
Max. density - min. density
Example: When noise level is set to 30
Edge
detection
region
Edge
detection
region
100%
50%
0%
no edge
noise level Edge
Max. density 60
60 15
Edge detected so
Min. density 15
measurement performed
Max. density 25
25 10
Min. density 10 Processed as no edge detected.
Measurement result: NG
Section 2-7
Maximum density value
Edge level
Minimum density value
NG measurement
Used for measurement
30
30