Main Content


Bottom-hat filtering



J = imbothat(I,SE) performs morphological bottom-hat filtering on the grayscale or binary image I, returning the filtered image, J. Bottom-hat filtering computes the morphological closing of the image (using imclose) and then subtracts the original image from the result. SE is a single structuring element object returned by the strel or offsetstrel functions.

J = imbothat(I,nhood) bottom-hat filters the image I, where nhood is a matrix of 0s and 1s that specifies the structuring element neighborhood. The imbothat function determines the center element of the neighborhood by floor((size(nhood)+1)/2).

This syntax is equivalent to imbothat(I,strel(nhood)).


collapse all

Read image into the workspace and display it.

I = imread('pout.tif');

Figure contains an axes. The axes contains an object of type image.

Create a disk-shaped structuring element.

se = strel('disk',3);

Add the original image I to the top-hat filtered image, and then subtract the bottom-hat filtered image.

J = imsubtract(imadd(I,imtophat(I,se)),imbothat(I,se));

Figure contains an axes. The axes contains an object of type image.

Input Arguments

collapse all

Input image, specified as a grayscale image or binary image of any dimension.

Data Types: single | double | int8 | int16 | int32 | uint8 | uint16 | uint32 | logical

Structuring element, specified as a single strel object or offsetstrel object. If the image I is data type logical, the structuring element must be flat.

Structuring element neighborhood, specified as a matrix of 0s and 1s.

Example: [0 1 0; 1 1 1; 0 1 0]

Output Arguments

collapse all

Bottom-hat filtered image, returned as a grayscale image or binary image. J has the same class as input image I.

Extended Capabilities

See Also



Introduced before R2006a