imhmax

H-maxima transform

Description

example

J = imhmax(I,H) suppresses all maxima in the intensity image I whose height is less than H. Regional maxima are connected components of pixels with a constant intensity value, and whose external boundary pixels all have a lower value.

J = imhmax(I,H,conn) computes the H-maxima transform, where conn specifies the connectivity.

Examples

collapse all

Create simple sample array of zeros with several maxima.

a = zeros(10,10);
a(2:4,2:4) = 3;  
a(6:8,6:8) = 8
a = 10×10

     0     0     0     0     0     0     0     0     0     0
     0     3     3     3     0     0     0     0     0     0
     0     3     3     3     0     0     0     0     0     0
     0     3     3     3     0     0     0     0     0     0
     0     0     0     0     0     0     0     0     0     0
     0     0     0     0     0     8     8     8     0     0
     0     0     0     0     0     8     8     8     0     0
     0     0     0     0     0     8     8     8     0     0
     0     0     0     0     0     0     0     0     0     0
     0     0     0     0     0     0     0     0     0     0

Calculate the maxima equal to 4 or more. Note how the area of the image set to 3 is not included.

b = imhmax(a,4)
b = 10×10

     0     0     0     0     0     0     0     0     0     0
     0     0     0     0     0     0     0     0     0     0
     0     0     0     0     0     0     0     0     0     0
     0     0     0     0     0     0     0     0     0     0
     0     0     0     0     0     0     0     0     0     0
     0     0     0     0     0     4     4     4     0     0
     0     0     0     0     0     4     4     4     0     0
     0     0     0     0     0     4     4     4     0     0
     0     0     0     0     0     0     0     0     0     0
     0     0     0     0     0     0     0     0     0     0

Input Arguments

collapse all

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

Example: I = imread('glass.png');

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

H-maxima transform, specified as a nonnegative scalar.

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

Pixel connectivity, specified as one of the values in this table. The default connectivity is 8 for 2-D images, and 26 for 3-D images.

Value

Meaning

Two-Dimensional Connectivities

4-connected

Pixels are connected if their edges touch. The neighborhood of a pixel are the adjacent pixels in the horizontal or vertical direction.

8-connected

Pixels are connected if their edges or corners touch. The neighborhood of a pixel are the adjacent pixels in the horizontal, vertical, or diagonal direction.

Three-Dimensional Connectivities

6-connected

Pixels are connected if their faces touch. The neighborhood of a pixel are the adjacent pixels in:

  • One of these directions: in, out, left, right, up, and down

18-connected

Pixels are connected if their faces or edges touch. The neighborhood of a pixel are the adjacent pixels in:

  • One of these directions: in, out, left, right, up, and down

  • A combination of two directions, such as right-down or in-up

26-connected

Pixels are connected if their faces, edges, or corners touch. The neighborhood of a pixel are the adjacent pixels in:

  • One of these directions: in, out, left, right, up, and down

  • A combination of two directions, such as right-down or in-up

  • A combination of three directions, such as in-right-up or in-left-down

For higher dimensions, imhmax uses the default value conndef(ndims(I),'maximal').

Connectivity can also be defined in a more general way for any dimension by specifying 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 about its center element. See Specifying Custom Connectivities for more information.

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

Output Arguments

collapse all

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

References

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

Extended Capabilities

Introduced before R2006a