Learn more about Video and Image Processing Blockset

Bottom-hat - Perform bottom-hat filtering on intensity or binary images

Library

Morphological Operations

Description

Use the Bottom-hat block to perform bottom-hat filtering on an intensity or binary image using a predefined neighborhood or structuring element. Bottom-hat filtering is the equivalent of subtracting the input image from the result of performing a morphological closing operation on the input image. This block uses flat structuring elements only.

Port	Input/Output	Supported Data Types	Complex 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	Scalar, vector, or matrix that represents the filtered image	Same as I port	No

If your input image is a binary image, for the Input image type parameter, select Binary. If your input image is an intensity image, select Intensity.

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 region the block moves throughout 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.

Dialog Box

The Bottom-hat dialog box appears as shown in the following figure.

Input image type

If your input image is a binary image, select Binary. If your input image is an intensity image, select Intensity.

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.

See Also

Closing	Video and Image Processing Blockset software
Dilation	Video and Image Processing Blockset software
Erosion	Video and Image Processing Blockset software
Label	Video and Image Processing Blockset software
Opening	Video and Image Processing Blockset software
Top-hat	Video and Image Processing Blockset software
imbothat	Image Processing Toolbox software
strel	Image Processing Toolbox software

Block Processing

Chroma Resampling

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