User`s manual

G-4
Glossary
G
[An example of detecting a point using the edge detection function and user specified criteria]
Edge emphasis
See "Space filter."
Edge extraction
See "Space filter."
Expansion
See "Expansion and contraction to eliminate binary noise in the image."
Expansion and contraction to eliminate binary noise in the image
When an image is converted to black and white, a number of unwanted dots may appear in the
image. These noises can be eliminated during the preliminary processing. Dot control processing of
binary values is used to eliminate this problem, as described below.
Expansion
If a white area contains a single, isolated black point, the system will interrupt the black point to
white.
Contraction
If a black area contains a single, isolated white point, the system will convert the white point to
black.
A
Edge detection point
Edge detection
point
B
A
B
A
Light
↑
Brightness
level
↓
Dark
Light
↑
Brightness
level
↓
Dark
Direction B
Edge
width
Flat
width
AB
A
B
A
Difference
in level
Direction
Edge
width
Flat
width
Difference
in level
B
Detection direction
Detection direction
Edge detection point
Detection area
Internal diameter (between B and C)
External diameter (between A and D)
Detection area
Detection area
Detection area
- Horizontal transition point
from light to dark (moving
from left to right)
- Vertical transition point from
light to dark (moving from top
to bottom)
- Horizontal transition point
from light to dark (moving
from right to left)
- Center (dark), horizontal (left and right)
- Edge detection of the inside and outside edges of a two circles
- Vertical transition point from
light to dark (moving from
bottom to top)
Detection
direction
Detection
direction
A: Moving right horizontally
from light to dark
B: Moving right horizontally
from dark to light
C: Moving left horizontally
from dark to light
D: Moving left horizontally
from light to dark
Edge detection
point