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# Dilation

Find local maxima in binary or intensity image

## Library

Morphological Operations

`visionmorphops`

## Description

The Dilation block rotates the neighborhood or structuring element 180 degrees. Then it slides the neighborhood or structuring element over an image, finds the local maxima, and creates the output matrix from these maximum values. If the neighborhood or structuring element has a center element, the block places the maxima there, as illustrated in the following figure.

If the neighborhood or structuring element does not have an exact center, the block has a bias toward the lower-right corner, as a result of the rotation. The block places the maxima there, as illustrated in the following figure.

This block uses flat structuring elements only.

PortInput/OutputSupported Data TypesComplex Values Supported

I

Vector or matrix of intensity values

• Double-precision floating point

• Single-precision floating point

• Fixed point

• Boolean

• 8-, 16-, and 32-bit signed integer

• 8-, 16-, and 32-bit unsigned integer

No

Nhood

Matrix or vector of ones and zeros that represents the neighborhood values

Boolean

No

Output

Vector or matrix of intensity values that represents the dilated image

Same as I port

No

The output signal has the same data type as the input to the I port.

Use the Neighborhood or structuring element source parameter to specify how to enter your neighborhood or structuring element values. If you select `Specify via dialog`, the Neighborhood or structuring element parameter appears in the dialog box. If you select ```Input port```, the Nhood port appears on the block. Use this port to enter your neighborhood values as a matrix or vector of 1s and 0s. You can only specify a structuring element using the dialog box.

Use the Neighborhood or structuring element parameter to define the neighborhood or structuring element that the block applies to the image. Specify a neighborhood by entering a matrix or vector of 1s and 0s. Specify a structuring element with the `strel` function from the Image Processing Toolbox™. If the structuring element is decomposable into smaller elements, the block executes at higher speeds due to the use of a more efficient algorithm. If you enter an array of STREL objects, the block applies each object to the entire matrix in turn.

## Parameters

Neighborhood or structuring element source

Specify how to enter your neighborhood or structuring element values. Select `Specify via dialog` to enter the values in the dialog box. Select `Input port` to use the Nhood port to specify the neighborhood values. You can only specify a structuring element using the dialog box.

Neighborhood or structuring element

If you are specifying a neighborhood, this parameter must be a matrix or vector of 1s and 0s. If you are specifying a structuring element, use the `strel` function from the Image Processing Toolbox. This parameter is visible if, for the Neighborhood or structuring element source parameter, you select ```Specify via dialog```.

## References

[1] Soille, Pierre. Morphological Image Analysis. 2nd ed. New York: Springer, 2003.

 Bottom-hat Computer Vision Toolbox™ software Closing Computer Vision Toolbox software Erosion Computer Vision Toolbox software Label Computer Vision Toolbox software Opening Computer Vision Toolbox software Top-hat Computer Vision Toolbox software `imdilate` Image Processing Toolbox software `strel` Image Processing Toolbox software