FindCircleMinMax
Inspects the circularity of a continuous edge by finding the minimum and maximum deviations from the edge and the standard deviation of the radii of all points on the edge.
FindCircleMinMax Inputs
Syntax: FindCircleMinMax(Image,Fixture.Row,Fixture.Column,Fixture.Theta,Annulus.X,Annulus.Y,Annulus.Inner Radius,Annulus.Outer Radius,Polarity,Minimum Contrast,Edge Width,Show)
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Specifies a reference to a spreadsheet cell that contains an Image data structure; by default, this parameter references A0, the cell containing the AcquireImage Image data structure. This parameter can also reference other Image data structures, such as those returned by the Vision Tool Image functions or Coordinate Transforms Functions. |
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Defines the Region of Interest (ROI) relative to a Fixture input or the output of a Vision Tool function's image coordinate system. Setting the ROI relative to a Fixture ensures that if the Fixture is rotated or translated, the ROI will be rotated or translated in relation to the Fixture. For more information, see Fixture and Vision Tools. The default setting is (0,0,0), the top leftmost corner of the image.
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Also known as the Region of Interest (ROI), specifies the region of the image that undergoes analysis; creates an annular image region that can be translated and rotated. With this parameter selected, by pressing the Maximize Region button on the property sheet's toolbar, the region will automatically be stretched to cover the entire image.
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Note: The Fixture
and Annulus parameters must be defined
within the bounds of the image; otherwise, the function will return #ERR.
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Specifies the polarity of the edge to be located, moving from inside to outside the circle, relative to the scan direction of the Region; the function will only report edges of the specified polarity.
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Specifies the minimum greyscale contrast (0 to 255; default = 10) at each point along the circle. |
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Specifies the pixel distance (1 to 50; default = 3) over which an edge transition takes place. Edge Width is used to filter the image before edges are extracted. |
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Specifies the display mode for FindCircleMinMax graphical overlays on top of the image.
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FindCircleMinMax Outputs
Returns |
An Edges data structure containing a single circular edge, or #ERR if any of the input parameters are invalid. |
Results |
When FindCircleMinMax is initially inserted into a cell, a result table is created in the spreadsheet. |
FindCircleMinMax Vision Data Access Functions
The following Vision Data Access functions are automatically inserted into the spreadsheet to create the result table. For more information, see Edges.
CentRow |
GetRow(Edges) |
The center row of the circular edge. |
CentCol |
GetCol(Edges) |
The center column of the circular edge. |
Radius |
GetRadius(Edges) |
The radius of the circular edge. |
Min |
GetMin(Edges) |
The minimum deviation from the circular edge. |
Max |
GetMax(Edges) |
The maximum deviation from the circular edge. |
SDev |
GetSDev(Edges) |
The standard deviation from the radii of all points on a continuous edge. |
Score |
GetScore(Edges) |
A measure of circularity of a continuous edge based on the radius of the circular edge and the standard deviation. The score will be higher for a small standard deviation and lower for a large standard deviation. Score is calculated using the following formula: Score = 100*(1 - 2*SDev/Radius) |
Additional data elements can be accessed using the following Vision Data Access functions:
MinRow |
GetRow(Edges, 1) |
The row of the minimum radius point of the circular edge. |
MaxRow |
GetRow(Edges, 2) |
The row of the maximum radius point of the circular edge. |
MinCol |
GetCol(Edges, 1) |
The column of the minimum radius point of the circular edge. |
MaxCol |
GetCol(Edges, 2) |
The column of the maximum radius point of the circular edge. |
Contrast |
GetContrast(Edges) |
The average contrast between the foreground and background of the circular edge (in grey levels 0-255). Contrast is positive for black-to-white transitions and negative for white-to-black transitions. |