Rockwell Automation 5370-CVIM2 Module - Manual (Page 46)

5 Chapter Chapter 3
Image Acquisition Parameters
3–7
When you pick the button on the camera setup panel, the
camera image appears along with the adjustment cursors, as shown in
Figure 3.5.
Figure 3.5 Selecting Light Reference Adjustment
Inspected
object
(foreground)
Adjacent back-
ground
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The degree of contrast within any given image is a function of the difference
between the darkest and lightest pixels within that image. For example, if the
brightness level of the inspected object were 130 (on a scale of 0 to 255) and
the adjacent background were 165, the contrast difference between them may
not be sufficient to allow reliable inspection tool operations.
By adjusting the light reference appropriately, you can enhance the “natural”
image contrast by, in effect, expanding the existing narrow range
(130–to–165, in the preceding example) to a wider range such as 70 to 180,
thereby increasing the contrast and improving the inspection tool
performance.
Your main objective in adjusting the light reference is to optimize the contrast
between the inspected part of the workpiece and the adjacent background.