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imhmin

H-minima transform

Syntax

I2 = imhmin(I,h)
I2 = imhmin(I,h,conn)

Description

example

I2 = imhmin(I,h) suppresses all minima in the intensity image I whose depth is less than h, where h is a scalar. Regional minima are connected components of pixels with a constant intensity value, t, whose external boundary pixels all have a value greater than t. By default, imhmin uses 8-connected neighborhoods for 2-D images, and 26-connected neighborhoods for 3-D images. For higher dimensions, imhmax uses conndef(ndims(I),'maximal').

I2 = imhmin(I,h,conn) computes the H-minima transform, where conn specifies the connectivity.

Examples

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Create a sample image with two regional minima.

a = 10*ones(10,10);
a(2:4,2:4) = 7;  
a(6:8,6:8) = 2
a = 

    10    10    10    10    10    10    10    10    10    10
    10     7     7     7    10    10    10    10    10    10
    10     7     7     7    10    10    10    10    10    10
    10     7     7     7    10    10    10    10    10    10
    10    10    10    10    10    10    10    10    10    10
    10    10    10    10    10     2     2     2    10    10
    10    10    10    10    10     2     2     2    10    10
    10    10    10    10    10     2     2     2    10    10
    10    10    10    10    10    10    10    10    10    10
    10    10    10    10    10    10    10    10    10    10

Suppress all minima below a specified value. Note how the region with pixels valued 7 disappears in the transformed image because its depth is less than the specified h value.

b = imhmin(a,4)
b = 

    10    10    10    10    10    10    10    10    10    10
    10    10    10    10    10    10    10    10    10    10
    10    10    10    10    10    10    10    10    10    10
    10    10    10    10    10    10    10    10    10    10
    10    10    10    10    10    10    10    10    10    10
    10    10    10    10    10     6     6     6    10    10
    10    10    10    10    10     6     6     6    10    10
    10    10    10    10    10     6     6     6    10    10
    10    10    10    10    10    10    10    10    10    10
    10    10    10    10    10    10    10    10    10    10

Input Arguments

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Input array, specified as a nonsparse numeric array of any dimension.

Example: I = imread('glass.png'); BW = imhmin(I,80);

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | logical

h-minima transform, specified as a nonnegative scalar.

Example: b = imhmin(a,4)

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64

Connectivity, specified as a one of the scalar values in the following table. By default, imhmin uses 8-connected neighborhoods for 2-D images and 26-connected neighborhoods for 3-D images. For higher dimensions, imhmin uses conndef(numel(size(I)),'maximal'). Connectivity can be defined in a more general way for any dimension by using for conn a 3-by-3-by- ...-by-3 matrix of 0s and 1s. The 1-valued elements define neighborhood locations relative to the center element of conn. Note that conn must be symmetric around its center element.

Value

Meaning

Two-dimensional connectivities

4

4-connected neighborhood

8

8-connected neighborhood

Three-dimensional connectivities

6

6-connected neighborhood

18

18-connected neighborhood

26

26-connected neighborhood

Example: b = imhmin(a,4,4)

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64

Output Arguments

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Transformed image, returned as a nonsparse numeric array of any class, the same size as I.

References

[1] Soille, P., Morphological Image Analysis: Principles and Applications, Springer-Verlag, 1999, pp. 170-171.

Extended Capabilities

Introduced before R2006a

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