Rockwell Automation 5370-CVIM2 Module - Manual (Page 309)

5 Chapter Chapter 7
Inspection Tools
7–71
Figure 7.59 illustrates the effect of the XY Edge kernel on a dark inspected
object on a light background.
Figure 7.59 Example: Effect of XY Edge Kernel on Inspected Object
Image tool
Inspected
object
In Figure 7.59, the XY Edge kernel causes the gradients on the all sides of
the inspected object to appear as a thin line of light pixels, while the pixels
surrounding the gradients were converted to medium gray.
Note that the Sign LUT has been selected. This LUT removes negative
values from the image by adding 128 to each value, thereby placing all
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. (When used with the
XY Edge kernel, however, the Absolute LUT yields a somewhat indistinct
double gradient compared to the S.Threshold LUT.) In any case, 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 XY Edge kernel are similar to those shown in
Figure 7.56 (page 7–67) for the Laplace kernel.