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mmlabel
Label a binary image.

Synopsis

y = mmlabel( f, Bc = None )

Implemented in Python.

Input

f Image Binary image.
Bc Structuring Element

( connectivity).

Default: None (Diamond structuring element with radius 1)

Output

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

If number of labels is less than 65535, the data type is uint16, otherwise it is int32.

Description

mmlabel creates the image y by labeling the connect components of a binary image f, according to the connectivity defined by the structuring element Bc. The background pixels (with value 0) are not labeled. The maximum label value in the output image gives the number of its connected components.

Equation

Where H is the number of image rows, and y1 and y2 are the row and column coordinates respectively.

Source Code

def mmlabel(f, Bc=None):
    from Numeric import allclose, ravel, nonzero, array
    if Bc is None: Bc = mmsecross()
    assert mmisbinary,'Can only label binary image'
    zero = mmsubm(f,f)               # zero image
    faux=f
    r = array(zero)
    label = 1
    y = mmgray( f,'uint16',0)        # zero image (output)
    while not allclose(faux,0):
        x=nonzero(ravel(faux))[0]      # get first unlabeled pixel
        fmark = array(zero)
        fmark.flat[x] = 1              # get the first unlabeled pixel
        r = mminfrec( fmark, faux, Bc) # detects all pixels connected to it
        faux = mmsubm( faux, r)        # remove them from faux
        r = mmgray( r,'uint16',label)  # label them with the value label
        y = mmunion( y, r)             # merge them with the labeled image
        label = label + 1
    return y

See also

mmlabelflat Label the flat zones of gray-scale images.
mmfreedom Control automatic data type conversion.
mmsebox Create a box structuring element.
mmsecross Cross structuring element.
mmareaopen Area opening
mmblob Blob measurements from a labeled image.
[mmhistogram] [Up] [mmblob] Python
Copyright (c) 2003, Roberto A. Lotufo, UNICAMP-University of Campinas; Rubens C. Machado, CenPRA-Renato Archer Research Center.