Module: Outer_Edge

Description:

Finds the outer edge of an object from an input image. The object is defined by thresholding, and the output data type is always unsigned bytes.
The outer edge, in n-connectivity, is defined by the set of pixels of the object that are ñ-adjacent either to the image border, either to the ñ-connected components of the background in contact with the image border. ñ is the neighbourhood relation dual to n.

Illustration. Left: input image. Right: outer edge.

NOTES

Because the definition of outer edge relies only on ñ, the outer edge in 18- or 26- connectivity will be identical, so choosing either connectivity will give the same result.

Connections:

Image

[required]
Input image, of type HxUniformScalarField3.

Ports:

Threshold

Used to define, along with the comparison operator, which pixels are in the object.

Comparison

Used to define how the threshold value is used for defining the object.

Values

Used to define the values in the output for the edge pixels and the rest.

Connectivity

Specifies the connectivity of the outer edge, which can be 6- or 26-connectivity (18-connectivity is not available, it will produce the same as 26-connectivity).

Illustration of the different connectivities in 3D. (a): 6-, (b): 18-, and (c): 26-connectivity.

Action button

Push this button to start the computation.

Commands:

Additional options can be accessed when typing in the console Outer_Edge COMMAND_NAME. Typing the command again usually reverts back to original settings.

`verbose`

Displays timing information after the computation. Retype to hide info.

`create`

Runs the computation. Returns the name of the output, so it can be used in a script, such as set RESULT [Outer_Edge create].