11.78. ITK Zero Crossing Image Filter
Marks the pixels that sit at sign changes (zero crossings) of a signed image, which typically correspond to edges.
Group (Subgroup)
ITKImageFeature (ImageFeature)
Description
A zero crossing is a place where a signed image changes sign — going from positive to negative or vice versa. When the input is a second-derivative image such as a Laplacian, these sign changes line up with the edges in the original image, so detecting them is a common edge-finding step.
This filter examines each pixel and its immediate neighbors using city-block (face) connectivity — 4 neighbors in 2D, 6 in 3D. Where a sign change is found, the pixel nearest the crossing is labeled as foreground; every other pixel is labeled as background. The result is a thin, binary edge map.
The input must be a signed image. Zero crossings are not defined for unsigned data, since unsigned values never go negative.
Use this filter after computing a Laplacian (or other signed response) to extract edge locations.
Parameter Guidance
Foreground Value — the label written to pixels that lie on a zero crossing (the detected edges). Default 1.
Background Value — the label written to all other pixels. Default 0.
Required Input Sources
Requires a signed scalar image whose sign changes are meaningful — most commonly the output of a Laplacian-of-Gaussian step such as ITK Laplacian Recursive Gaussian Image Filter.
See Also
Input Parameter(s)
Parameter Name |
Parameter Type |
Parameter Notes |
Description |
|---|---|---|---|
Foreground Value |
UInt8 |
Set/Get the label value for zero-crossing pixels. |
|
Background Value |
UInt8 |
Set/Get the label value for non-zero-crossing pixels. |
Input Cell Data
Parameter Name |
Parameter Type |
Parameter Notes |
Description |
|---|---|---|---|
Image Geometry |
Geometry Selection |
Image |
Select the Image Geometry Group from the DataStructure. |
Input Cell Data |
Array Selection |
Allowed Types: int8, int16, int32, int64, float32, float64 |
The image data that will be processed by this filter. |
Output Cell Data
Parameter Name |
Parameter Type |
Parameter Notes |
Description |
|---|---|---|---|
Output Image Data Array |
DataObjectName |
The result of the processing will be stored in this Data Array. |
Example Pipelines
License & Copyright
Please see the description file distributed with this Plugin
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