```{index} single: Filters; ITK Black Top Hat Image Filter
```
# ITK Black Top Hat Image Filter

Black top hat extracts local minima that are smaller than the structuring element.

## Group (Subgroup)

ITKMathematicalMorphology (MathematicalMorphology)

## Description

Black top hat extracts local minima that are smaller than the structuring element. It subtracts the background from the input image. The output of the filter transforms the black valleys into white peaks.

Top-hats are described in Chapter 4.5 of Pierre Soille's book "Morphological Image Analysis: Principles and Applications", Second Edition, Springer, 2003.

### Author

 Gaetan Lehmann. Biologie du Developpement et de la Reproduction, INRA de Jouy-en-Josas, France.

### Related Filters

![](Images/ITKBlackTopHat_1.png)
![](Images/ITKBlackTopHat_2.png)


### 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

## License & Copyright

Please see the description file distributed with this plugin.

## DREAM3D-NX Help

If you need help, need to file a bug report or want to request a new feature, please head over to the [DREAM3DNX-Issues](https://github.com/BlueQuartzSoftware/DREAM3DNX-Issues/discussions) GitHub site where the community of DREAM3D-NX users can help answer your questions.