# imhmax

H-maxima transform

## Syntax

``J = imhmax(I,H)``
``J = imhmax(I,H,conn)``

## 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`

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

Current pixel is shown in gray.

`8`

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.

Current pixel is shown in gray.

Three-Dimensional Connectivities

`6`

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

Current pixel is shown in gray.

`18`

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

Current pixel is center of cube.

`26`

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

Current pixel is center of cube.

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 `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. 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.

## Version History

Introduced before R2006a