11.77. ITK White Top Hat Image Filter

Extracts small bright features by subtracting the grayscale opening from the original image.

Group (Subgroup)

ITKMathematicalMorphology (MathematicalMorphology)

Description

The white top-hat isolates small bright features — bright spots and narrow bright ridges smaller than the structuring element (the probe shape swept over the image). It is computed as the original image minus its grayscale opening, which leaves the small bright details on a flat (near-zero) background. A common use is correcting uneven (bright) background illumination or extracting small bright details for measurement. The dark-feature counterpart is ITK Black Top Hat Image Filter.

Parameter Guidance

  • Kernel Radius — the radius of the structuring element, in pixels (one value per axis). It sets the size scale: features smaller than the structuring element are extracted, larger structures are removed.

  • Safe Border — when on (default), a temporary border is added during processing to avoid edge artifacts and removed afterward.

Kernel Type

The Kernel Type parameter selects the structuring element shape:

  • Annulus [0]: A ring-shaped structuring element.

  • Ball [1]: A spherical structuring element (default). Most commonly used for general morphological operations.

  • Box [2]: A rectangular/cuboid structuring element.

  • Cross [3]: A cross-shaped structuring element.

Required Input Sources

Operates on any scalar (grayscale) image — typically from Read Image, Read Images [3D Stack], or the output of a prior ITK image filter.

White top-hat example.

Reference

Pierre Soille, Morphological Image Analysis: Principles and Applications, Second Edition, Springer, 2003 (Chapter 4.5).

Input Parameter(s)

Parameter Name

Parameter Type

Parameter Notes

Description

Kernel Radius

Vector of UInt32 Values

Order=X,Y,Z

The radius of the kernel structuring element.

Kernel Type

Choices

Set the kernel or structuring element used for the morphology.

Safe Border

Bool

A safe border is added to input image to avoid borders effects and remove it once the closing is done

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, uint8, int16, uint16, int32, uint32, int64, uint64, float32, float64

The image data that will be processed by this filter.

Output Cell Data

Parameter Name

Parameter Type

Parameter Notes

Description

Output Cell Data

DataObjectName

The result of the processing will be stored in this Data Array inside the same group as the input data.

Example Pipelines

DREAM3D-NX Help

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