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(8) Edge detection
The "edge" refers to the boundaries between the brighter (white) and darker (black) parts in an
image. The "edge detection" function is used to detect this boundary by processing the image.
[An example of detecting a point using the edge detection function and user specified
criteria]
· Horizontal transition point
from light to dark (moving
from left to right)
Edge detection point
A
B
Detection direction
· Horizontal transition point
from light to dark (moving
from right to left)
Detection area
A
B
Edge detection
point
Detection direction
· Center (dark), horizontal (left and right)
Edge detection point
Detection area
· Edge detection of the inside and outside edges of a two circles
A: Moving right horizontally
from light to dark
Detection area
- The edge detection point coordinates are used as a reference point to detect an out of position
condition.
- Edge detection in binary images is much quicker than in a gray scale search. However, the
binary image detection process is less precise at detecting position.
[Measurement programs which are affected by these settings]
Positional deviation measurement (edge detection: page 9-39),
Distance and angle measurement (edge detection page 9-61)
Lead inspection (edge detection: page 9-76).
· Vertical transition point from
light to dark (moving from top
to bottom)
Edge detection
point
A
Detection area
B
· Vertical transition point from
light to dark (moving from
bottom to top)
A
B
B: Moving right horizontally
from dark to light
9-11
Edge
width
Light
Brightness
level
Dark
A
Direction
Edge
Light
width
Brightness
level
Dark
A
Direction
C: Moving left horizontally
from dark to light
D: Moving left horizontally
from light to dark
Internal diameter (between B and C)
External diameter (between A and D)
Shared settings
Flat
width
Difference
in level
B
Flat
width
Difference
in level
B
9
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