Image Preprocessing (Slice Level / Preprocess); Binarizing An Image (Slice Level) - Panasonic PV500 User Manual

4.6 Image Preprocessing (Slice Level / Preprocess)

PV500 takes in signals from a camera as an image with 256 intensities
(0 to 255). The image is "gray image" and the 256 intensities are "gray
value". The higher gray value indicates the brighter pixel, and the
lower gray value the darker pixel.
The function that applies filtering process on an image in order to
execute desired inspections based on the gray image is "Preprocess".
Among them, the process that makes a gray image into a
monochrome image is binarization and a binarized image is a binary
image. Some of inspection functions scan with this binary image.

4.6.1 Binarizing an Image (Slice Level)

In PV500, up to 26 sets of slice level (A to Z) can be registered, which is called slice level group. Which slice
level group is used to inspect an image is set in the checker setting window.
Gray Image
The values are gray level of each
pixel.
Setting a Slice Level
1.
Select "INSPECTION" > "Slice Level" from the menu bar.
"Slice Level" setting window is displayed.
Slice level can be modified also in setting window of a
checker which scans with a binary image.
2.
Select a group to set from the table.
"Slice Level" setting sub-window is displayed.
3.
Select "Auto Adjustment".
If the image turned to be a desired binary image, setting
is completed.
4.
Select "Minimum" to specify the minimum value.
Specify the maximum value as necessary.
Changing values updates the displayed image.
Beneath the table, a histogram is displayed. The two red lines indicate the minimum value and the
maximum value. Refer to the histogram as necessary.
5.
After setting is completed, press the CANCEL key.
80
Slice Level Group A
Maximum value is 255
Minimum value is 200
200 to 255 = white
0 to 199 = black
Slice Level Group B
Maximum value is 255
Minimum value is 150
150 to 255 = white
0 to 149 = black
The pixel with 170 of gray level will
be "white".