Threshold Type: Edge Strength
Measures the rate of change of grayscale values and needs
sharply-defined
transitions
to
find
edges.
Figure 187. Edge Strength Threshold Parameters
Edge strength ignores gradual changes in light levels across the tool
better
than other threshold types and it
filters
out weak or gradual
edges.
Edge Strength Threshold: Edge Strength
Enter an edge strength value from 1 to 255.
Edges are selected by the edge strength method, which measures the rate of change from bright to dark or dark to bright. Enter an edge
strength threshold in the range from 1 to 255. The default value is 20. As this value is reduced, the tool
finds
weak, blurry, or more
gradual edges.
Edge Polarity
Edge Polarity
defines
the type of edges that the tool
finds.
• Dark to Bright—Finds edges where pixel
intensities
start below the threshold value and cross above the threshold value
• Bright to Dark—Finds edges where pixel
intensities
start above the threshold value and cross below the threshold value
• Bright or Dark—Finds any edge
Edge Strength Threshold: Edge
Profile
Graph
Figure 188. Edge Strength Threshold—Edge
Profile
Graph
For edge strength threshold, the x axis is the length of the ROI. The y axis has two measurements. The
first
is the light blue axis. It
represents Edge Strength, a measure of the rate of change of pixel grayscale values. The second is the dark gray axis. It represents Edge
Profile,
which gives the absolute grayscale level across the tool ROI. The blue line is the rate of change of the grayscale value along the
ROI. The two horizontal gray lines are the edge strength threshold plus and minus.
Point to a
location
on the graph—the corresponding
location
is the yellow line on the tool ROI displayed on the image.
VE Series Smart Camera
104
www.bannerengineering.com - Tel: 763.544.3164