imimposemin (Image Processing Toolbox)

Impose minima

Syntax

```
I2 = imimposemin(I,BW)
```

Description

I2 = imimposemin(I,BW) modifies the intensity image I using morphological reconstruction so it only has regional minima wherever BW is nonzero. BW is a binary image the same size as I.

By default, imimposemin uses 8-connected neighborhoods for 2-D images and 26-connected neighborhoods for 3-D images. For higher dimensions, imimposemin uses conndef(ndims(I),'mimimum').

I2 = imimposemin(I,H,CONN) specifies the connectivity, where CONN may 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

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 may also 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. BW must be a nonsparse numeric array with the same size as I. I2 has the same size and class as I.

Example

Modify the image in bonemarr.tif so that is only has regional minima at one location.

First read in and display the image to be processed, called the mask image.

I = imread('bonemarr.tif');
imshow(I)

Create the marker image that will be used to process the mask image. The example creates a binary image the same size as the mask image, filled with zeros. It then sets a small area of the binary image to 1; these pixels define the location of the minima in the mask image.

bw = zeros(size(I));
bw(98:102,101:105) = 1;

To show where these pixels of interest fall on the original image, this code superimposes the marker over the mask. The small white square marks the spot. This code is not essential to the impose minima operation.
- ```
J = I;
J(bw ~= 0) = 255;
figure, imshow(J)
```

Impose the minina on the input image by performing morphological reconstruction of the mask image with the marker image. Note how all the dark areas of the original image, except those marked, are lighter.

K = imimposemin(I,bw);
figure, imshow(K)

To illustrate how this operation removes all minima in the original image except the imposed minima, the example uses imregionalmin to find all regional minima in the image.
- ```
bw2 = imregionalmin(K);
figure, imshow(bw2)
```

Algorithm

imimposemin uses a technique based on morphological reconstruction.

imhmin imlincomb