Hardware manual

Subpixel Edge Extractor Impact Reference Guide
Datalogic Automation Inc. 3-144
Edge Extraction Examples
Subpixel Position
The subpixel position gives you greater control over subpixel position for edges that are not well defined.
The bottom, middle, and top of the edge are determined by the direction of the Wide Line ROI and the Edge
Polarity setting. (See the examples below.) There are three settings:
1. Middle of Step Edge: This is the default setting and the correct choice for most cases. The tool finds
the steepest part of the edge (the area with the greatest grey level change).
2. Bottom of Ramp Edge: This setting finds the beginning of the edge.
3. Top of Ramp Edge: This setting finds the end of the edge.
In the following examples, the edge of the part is not well defined because it is rounded and therefore
becomes darker near the edge. The Middle of Step Edge setting finds the steepest part of the edge which
actually occurs inside the part in this case. The Bottom of Ramp Edge setting finds the beginning of the ris-
ing edge, which is the desired edge in this case. The Top of Ramp Edge setting finds the end of the rising
Fixed Grey Level
Threshold Percent-
age
The threshold value used when Grey Level Edge Detection and Fixed
Threshold Edge Detection Sensitivity are selected
Subpixel Position The subpixel position for edges that are not well defined. See “Subpixel
Position” on page 3-144.
Output Name What it is
Edge Point List List of edge points found
Input Name What it is
Wide Line ROIs
Edges Found