Image Processing Toolbox

imhmin

H-minima transform

Syntax

• I2 = imhmin(I,h)
  

Description

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 the same 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, imhmin uses conndef(ndims(I),'maximal').

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

Connectivity may 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 = 10*ones(10,10);
  a(2:4,2:4) = 7;  % maxima 3 lower than surround
  a(6:8,6:8) = 2;  % maxima 8 lower than surround
  b = imhmin(a,4); % only the minima lower than 4 survive.
  

See Also

conndef, imhmax, imreconstruct

Reference

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

imhmax

imimposemin