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ialabel
Label a binary image.

Synopsis

g = ialabel( f )

Implemented in Python.

Input

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

Output

g	Image. Accepts any image data type.

Description

Creates an image by labeling the connect components of the input binary image. The background pixels (with value 0) are not labeled. The maximum label value in the output image gives the number of its connected components.

Examples

>>> f = Numeric.array([[0,1,0,1,1], [1,0,0,1,0]])

>>> print f

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

>>> g = ialabel(f)

>>> print g

[[0 1 0 2 2]
 [3 0 0 2 0]]

>>> f = iaread('blobs.pbm')

>>> g = ialabel(f);

>>> nblobs = max(Numeric.ravel(g))

>>> print nblobs

>>> iashow(f)

(128, 128) Min= 0 Max= 1 Mean=0.482 Std=0.50

>>> iashow(ialblshow(g))

(3, 128, 128) Min= 0.0 Max= 248.0 Mean=53.995 Std=72.93


f	ialblshow(g)

Source Code
        def ialabel(f):
    from Numeric import zeros, nonzero, ravel
    faux = 1*f
    g    = zeros(faux.shape)
    gaux = zeros(faux.shape)
    i = nonzero(ravel(faux))
    k = 1
    while len(i):
        aux = iaind2sub(faux.shape, i[0])
        gaux = iarec(faux, (aux[0],aux[1]))
        faux = faux - gaux
        g = g + k*gaux
        k += 1
        i = nonzero(ravel(faux))
    return g
    
      

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