[mmareaclose] [Up] [mmasfrec] Connected Operators

mmareaopen
Area opening

Synopsis

y = mmareaopen( f, a, Bc = None )

Implemented in Python.

Input

f Image Gray-scale (uint8 or uint16) or binary image.

Double

non negative integer.

Structuring Element

( connectivity).

Default: None (3x3 elementary cross)

Output

y	Image Same type of `f`

Description

mmareaopen removes any grain (i.e., connected component) with area less than a of a binary image f. The connectivity is given by the structuring element Bc. This operator is generalized to gray-scale images by applying the binary operator successively on slices of f taken from higher threshold levels to lower threshold levels.

Examples

Numerical examples:

>>> f=mmbinary(uint8([
 [1, 1, 0, 0, 0, 0, 1],
 [1, 0, 1, 1, 1, 0, 1],
 [0, 0, 0, 0, 1, 0, 0]]))

>>> y=mmareaopen(f,4,mmsecross())

>>> print y

[[0 0 0 0 0 0 0]
 [0 0 1 1 1 0 0]
 [0 0 0 0 1 0 0]]

>>> f=uint8([
   [10,   11,   0,    0,   0,   0,  20],
   [10,    0,   5,    8,   9,   0,  15],
   [10,    0,   0,    0,  10,   0,   0]])

>>> y=mmareaopen(f,4,mmsecross())

>>> print y

[[10 10  0  0  0  0  0]
 [10  0  5  5  5  0  0]
 [10  0  0  0  5  0  0]]

Binary image

>>> a=mmreadgray('form-1.tif');

>>> b=mmareaopen(a,500);

>>> mmshow(a);

>>> mmshow(b);


a	b

Gray-scale image

>>> a=mmreadgray('bloodcells.tif');

>>> b=mmareaopen(a,500);

>>> mmshow(a);

>>> mmshow(b);


a	b

Equation

Limitations

The structuring elements allowed are the elementary cross (4-connected) and the elementary box (8-connected).

Source Code
        def mmareaopen(f, a, Bc=None):
    if Bc is None: Bc = mmsecross()
    if mmisbinary(f):
      fr = mmlabel(f,Bc)      # binary area open, use area measurement
      g = mmblob(fr,'area')
      y = mmthreshad(g,a)
    else:
      y = mmintersec(f,0)
      zero = mmbinary(y)
      k1 = mmstats(f,'min')
      k2 = mmstats(f,'max')
      for k in range(k1,k2+1):   # gray-scale, use thresholding decomposition
        fk = mmthreshad(f,k)
        fo = mmareaopen(fk,a,Bc)
        if mmisequal(fo,zero):
          break
        y = mmunion(y, mmgray(fo,mmdatatype(f),k))
    return y
    
      

mmfreedom	Control automatic data type conversion.
mmlabel	Label a binary image.
mmsebox	Create a box structuring element.
mmsecross	Diamond structuring element and elementary 3x3 cross.
mmareaclose	Area closing

[`mmareaclose`] [Up] [`mmasfrec`]
Copyright (c) 2003, Roberto A. Lotufo, UNICAMP-University of Campinas; Rubens C. Machado, CenPRA-Renato Archer Research Center.

mmareaopen Area opening