mmskelm - Morphological skeleton (Medial Axis Transform).

Synopsis

y = mmskelm( f, B, option )

Input

f: Binary image (logical uint8).

B: Structuring element. Default: Elementary cross (mmsecross).

option: String. Choose one of: binary: output a binary image (medial axis); value: output a grayscale image with values of the radius of the disk to reconstruct the original image (medial axis transform). Default: "binary".

Output

y: Gray-scale (uint8 or uint16) or binary image (logical uint8).

Description

mmskelm creates the image y by computing the morphological skeleton by B of the image f, when option is BINARY. In this case, the pixels of value 1 in y are center of maximal balls (generated from B) included in f. This is also called Medial Axis. If option is VALUE, the non zeros pixels in y are the radius plus 1 of the maximal balls. This is called Medial Axis Transform or valued morphological skeleton.

Examples

a=mmneg(mmframe(mmbinary(ones(7,9)))) Warning: Converting image from double to uint16. a = 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 0 0 1 1 1 1 1 1 1 0 0 1 1 1 1 1 1 1 0 0 1 1 1 1 1 1 1 0 0 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 mmskelm(a) ans = 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 1 0 0 0 1 0 0 0 0 0 1 1 1 0 0 0 0 0 1 0 0 0 1 0 0 0 1 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 mmskelm(a,mmsebox) ans = 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 1 1 1 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

a=mmreadgray('pcbholes.tif'); b=mmskelm(a); mmshow(a); mmshow(b); (a) (b)

c=mmskelm(a,mmsecross,'value'); mmshow(c); (c)

Equation

Algorithm

function y=mmskelm_equ(f, B)
  y = mmbinary(zeros(size(f)));
  for i=0:length(f)
    nb = mmsesum(B,i);
    f1 = mmero(f,nb);
    f2 = mmopenth(f1,B);
    y = mmunion(y,f2);
  end; 

See Also

mmcbisector - N-Conditional bisector.

mmfreedom - Control automatic data type conversion.

mmlastero - Last erosion.

mmskelmrec - Morphological skeleton reconstruction (Inverse Medial Axis Transform).

mmthin - Image transformation by thinning.

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