Detect Circular Edges in Grayscale Images

Note  The Circular Edge (Spoke) function works only with 8-bit images.

Main Tab

1. In the Step Name control, enter a descriptive name for the step.
2. Verify that the Reposition Region of Interest option is enabled if you want to link the region of interest specified in this step to a previously defined coordinate system.

   Link the region of interest to a coordinate system if the position of the object under inspection changes from image to image, and you need to adjust the position of the region of interest to match the new location of the object.

Settings Tab

1. Draw and adjust a region of interest using the annulus tool that includes the circular edge you want to find.

   When you specify a region of interest, the step automatically tries to locate a circular edge in the region. If the automatically-located edge corresponds to the edge you expected to find, skip the next step. Otherwise, go to the next step.

2. Disable the Auto Setup control and manually adjust the edge location parameters.
   1. Select the direction properties of the search lines. Select the search direction along the lines that has the least number of obstacles between the edge of the region and the object edge you want to find.
   2. If the Edge Strength Profile contains a strong peak that corresponds to the edge you want to find, adjust the yellow edge strength line so that it lies slightly below the top of the edge peak but above all of the other peaks.

      If the Edge Strength Profile does not contain a strong edge peak, adjust the Smoothing and Steepness controls until a peak appears.

      If the step still cannot find the edge or the location of the detected edge is inaccurate, adjust the gap between the search lines until you achieve the expected result.

Results Tab

1. Click the Results tab to view information about the center and radius of the circular edge the step found on the image.
2. Click OK to add this step to the script and close the parameter window.

Tip  You can modify and move the ROI using context sensitivity. Move the mouse close to the control points of the ROI to adjust their positions. You also can select the entire ROI by clicking the middle of the ROI and dragging it.