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(7) The expansion/contraction method of eliminating noise in binary images
When converting an image to binary values, it is often the case that dots of noise will show up in
the converted image. This noise may be eliminated during pre-processing by using the
smoothing function. However, it can also be dealt with through the expansion/contraction noise
elimination method.
-1 Expansion
2 Contraction
-1 Expansion _ contraction
2 Contraction _ expansion
The IV-S20 has both "contraction _ expansion" and "expansion _ contraction" functions for
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eliminating binary noise.
- Number of times of expansion and number of times of contraction can be set independenly.
When the number of contraction cycles is set to 0, and the number of expansion cycles is one
or greater, then only the expansion function will be used.
On the other hand, if the number of expansion cycles is set to 0 and the number of contraction
cycles is one or greater, then only the contraction function will be used.
[Measurement programs which are affected by these settings]
Degee of match inspection for shape and size (binary conversion: page 9-51)
Distance and angle measurement (center of gravity: page 9-62)
Area measurement by binary conversion (page 9-85)
Counting quantities by binary conversion (page 9-93)
Identifying object by binary conversion (page 9-101)
A single white dot, or small groups of white dots, in the middle of a black background can be
eliminated from the image.
A single black dot, or small groups of black dots, in the middle of a white background can be
eliminated from the image.
When isolated dots of noise are eliminated by expansion, the areas enlarged by the
expansion are returned to their original size by contracting them again.
When isolated white noise is eliminated by contraction, the areas shrunk by contraction are
returned to their original size by expanding them again.
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