Rockwell Automation 5370-CVIM2 Module - Manual (Page 303)

5 Chapter Chapter 7
Inspection Tools
7–65
Figure 7.54 Example: Effect of Sobel Y Kernel on Inspected Object
Image tool
Inspected
object
Note that the Sign LUT was selected for the example. Since the Sobel Y
kernel creates a signed image, which contains pixel values between –128 and
+127, the
Sign LUT removes negative values from the image by adding 128
to each value, thereby placing all pixel values in the 0 to 255 range that the
inspection tools require to identify and evaluate features properly.
Note also that the Absolute , S.Threshold , or S.Clip LUT could be used,
since they also remove negative values from the image. The choice of LUT
depends on the specific requirements for the application.
The effects on the inspected object that the Absolute and S.Threshold
LUTs have when using the Sobel Y kernel would be similar to the Sobel X
examples in Figure 7.53 (page 7–64).