Image Processing Toolbox User's Guide  imhmax

H-maxima transform

Syntax

• ```I2 = imhmax(I,h)
I2 = imhmax(I,h,CONN)
```

Description

`I2 = imhmax(I,h)` suppresses all maxima in the intensity image `I` whose height is less than `h`, where `h` is a scalar.

Regional maxima are connected components of pixels with a constant intensity value, and whose external boundary pixels all have a lower value

By default, `imhmax` 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 = imhmax(I,h,CONN)` computes the H-maxima transform, where `CONN` specifies the connectivity. `CONN` can have any of the following scalar values.

 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

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 `0`'s and `1`'s. The `1`-valued elements define neighborhood locations relative to the center element of `CONN`. Note that `CONN` must be symmetric about its center element.

Class Support

`I` can be of any nonsparse numeric class and any dimension. `I2` has the same size and class as `I`.

Example

• ```a = zeros(10,10);
a(2:4,2:4) = 3;  % maxima 3 higher than surround
a(6:8,6:8) = 8;  % maxima 8 higher than surround
b = imhmax(a,4); % only the maxima higher than 4 survive.
```

`conndef`, `imhmin`, `imreconstruct`