Sharp IV-S30J User Manual page 60

(6) 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.
Expansion
A single white dot, or small groups of white dots, in the middle of a black background can be
eliminated from the image.
Contraction
A single black dot, or small groups of black dots, in the middle of a white background can be
eliminated from the image.
The IV-S30J has both "contraction
eliminating binary noise.
Expansion contraction
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.
2 Contraction expansion
When isolated white noise is eliminated by contraction, the areas shrunk by contraction are
returned to their original size by expanding them again.
- Number of times of expansion and number of times of contraction can be set independently.
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
Area measurement by binary conversion, object counting by binary conversion, object
identification by binary conversion
Setting method
Select "DETAIL" in the upper function menu on
the REG COND screen, and choose "BINRY
NOISE FILT" to change the blank box to a filled
box. Then, " BINRY NOISE FILT" will appear
on the REG COND screen. Press the SET key
on this line and select "EXPD. -> CONTR." or
"CONTR -> EXPD." from the popup menu.
Setting the Conditions for Each Object Type
expansion" and "expansion
REG COND SCREEN COND SAVE DETAIL
1REGISTER NO.
00(0 15)
2MEAS SHAPE
RECTANGLE
3MEAS AREA
SET (224,208)~(287,271)
4THRESHOLD
SET [U.LM255 L.LM100(0~255)]
5INVERT B/W
NO
6BINARY NOISE FILT EXPD. CONTR
3-13
contraction" functions for
F C1 BRT
MASK REGIST.
BINARY PROCESS
BINARY NOISE
NO
EXPD. CONTR.
CONTR. EXPD.
3