2-16-(4)
EC Positioning
Section 2-16
2-16-2
Extracting Edges
EC positioning is performed for images for which the edges have been
extracted.
Adjust the upper and lower levels for edge extraction if there is low contrast
between the measurement object and the background and to remove noise.
Upper and Lower Limits for Edge Extraction Image
Set the level to which the background will be cut from the edge-extracted
image. The levels can be set between 10 and 255 (default 100:255).
Areas with a density above the lower limit will become the edge of the mea-
surement object. Refer to the following examples and adjust the upper and
lower limits.
Example: Cannot Find Edges Due to Low Contrast
Example: To Remove Noise
Example: Other Edges Clearly Extracted But Cannot Find Desired Mark
Edge with Stability
CHECK
If the lower limit is too low, low-level noise may remain even if the image
appears noise-free on the screen. If measurements are not stable, use the fol-
lowing methods to see if unwanted edges have been extracted and eliminate
them.
• Checking Method
Lower the upper limit to the same value as the lower limit. If unwanted
edges are displayed, then the lower limit is too low. Return the upper limit
to its original value after completing this check.
• Elimination Method
Increase the lower limit, or use smoothing or median filtering.
SeeAlso
Refer to
,QSXWWLQJ&DPHUD,PDJHV
and
)LOWHULQJ$JDLQ
(where smooth-
ing can be set to be executed twice).
Edge-extracted image
Reduce lower
limit.
Cannot find edges
Edge-extracted image
Increase lower
limit.
Low contrast with background
High contrast with background
Edge-extracted image
Reduce upper limit.
The edges of low contrast
sections also clearly
extracted.
