User`s manual

G-8
Glossary
G
Ë Pixel
On the CCD, the electrically charged elements are in close proximity, arranged in a matrix (480 lines in
vertical direction, 512 rows in horizontal direction). One element is equivalent to one pixel.
Binary
conver-
sion
Object
identifi-
cation
(in order of
scanning)
Object identification
(in order of area)
Island
1
1
2
2
3
3
4
4
Island
[O]
Ë Object identification and numbering function (labeling)
Object identification and numbering (labeling) is a process for locating separate object and assigning
serial numbers (labels) one at a time in a binary image. By this process, multiple objects in the same
binary image can be handled separately or as a group.
Whole image reading Partial image reading
512 512
480 120
[P]
Ë Partial CCD reading
The "partial CCD reading" technique reads only that part of the CCD which contains the object needed for
image processing. This can shorten the data transfer time from the CCD camera to the image memory.
To read the entire CCD image (480 horizontal lines) takes approximately 33 ms. With the partial reading
technique (e. g.: 120 horizontal lines) can take only 25 % of the time to read the entire image.
The IV-S30 can automatically determine the width of the partial image window. You can change back and
forth between reading the whole image and a partial image.
[N]
Ë
Normalization correlation
To determine whether the levels between the reference image and the input image match, the IV-S30
uses an information processing method called "normalization correlation." This is a method used to cal-
culate relationship between two groups of data.
- Factors determining the correlation value
If the densities of the two images have the same tendency (positive correlation), the two images are
said to resemble each other. If the densities of the two images have opposite tendencies (negative
correlation), the two images are said not to resemble each other. Therefore, areas of the reference
image and the input image which resemble each other (the areas of both images are brighter, or
darker) are positive, and areas which do not (the areas of one is brighter and the other is darker) are
negative.
- Correlation formula = { A ÷ B x C } x 10000
A = NΣ (I x T) — (ΣI) x (ΣT): Correlation between input image and reference image
B = NΣ (I x I) — (ΣI) x (ΣI): Correlation between input images
C = NΣ (T x T) — (ΣT) x (ΣT): Correlation between reference images
(N: Area of reference image, T: Density of reference image, I: Density of input image)