Banner PresencePLUS BCR 1.3 Series - Manual (Page 98)

Threshold Type
The threshold is used to mark the gray scale transition point. The tool marks the edge when the pixel intensity
crosses the threshold level. From the dropdown list, select one of the following:
• Relative
• Absolute
• Edge Strength
Relative Threshold
Relative threshold is the default, and it finds an edge at a relative pixel intensity. The brightest gray scale level
is 100% and the darkest is 0%. While Relative threshold is more tolerant of light fluctuations between inspections
than other transition types, it may find false edges.
Description Field/Graph
Percent is displayed when the Type is Relative. Choose the percentage value at
which the edge should be marked. Percent
Polarity
• Bright to Dark finds edges that start above the threshold value and cross below
the threshold value.
• Dark to Bright finds edges that start below the threshold value and cross above
the threshold value.
• Bright or Dark finds any edge.
In the Edge Profile graph displayed when the Relative threshold is selected, the
red line shows the percentage pixel intensity relative to the green threshold line.
The threshold line will move up or down with the percent value. Edge Profile Graph
Absolute Threshold
Absolute threshold finds an edge at a specific gray scale level. While Absolute threshold is less likely to find
a false edge than Relative Threshold, it may miss edges if the light level changes between inspections.
P/N 000000 Banner Engineering Corp. - Minneapolis, MN USA - www.bannerengineering.com
Tel: 763.544.3164
98
7/2009 PresencePLUS Software Tools