Rockwell Automation 5370-CVIM2 Module - Manual (Page 397)

5 Chapter Chapter 7
Inspection Tools
7–159
Foreground Objects; Background Objects
These two operations configure a profile tool to count the number of
“foreground” or “background” objects along the display image. The object
counting is performed along either the X–axis or the Y–axis of the image
field, according to the selection in the
Direction field.
In the context of profile tool object counting operations, the terms
“foreground object” and “background object” have specific meanings, as
follows:
•
Foreground object –– An area in the profile image where the gray scale
values of the “pixels” are “above” the threshold setting.
Foreground objects appear as areas in the profile display that are above
(in the X direction) or to the right (in the Y direction) of the threshold
display.
•
Background object –– An area in the profile image where the gray scale
values of the “pixels” are “below” the threshold setting.
Background objects appear as areas in the profile display that are below
(in the X direction) or to the left (in the Y direction) of the threshold
display.
These object counting operations are similar to the binary object counting
operations for a gage tool, in the sense that they both return the number of
foreground or background objects. (See Binary Gaging Mode: Foreground
Objects on page 7–8 and Binary Gaging Mode: Background Objects on
page 7–9, for a comparison.)
When the X direction is selected, the object counting operations count
objects along the X axis, as is illustrated in Figure 7.130 (page 7–160).
The example in Figure 7.130 illustrates a profile window positioned over a
row of rectangles on a “workpiece” and the resulting profile display. The
threshold display is shown intersecting the profile display graphic at the
default “gray scale” level (128).
In this example, the profile tool can identify either two foreground objects or
three background objects, according to the selected tool operation. The two
foreground objects correspond to the two lighter rectangles and the light
spaces on both sides of them. (Note that the light areas at each end do not
qualify as foreground objects, since they do not lie completely within the two
ends of the profile window.) The three background objects correspond to the
three darker rectangles.