[mmlabel] [Up] [mmlabelflat] Measurements

mmblob
Blob measurements from a labeled image.

Synopsis

y = mmblob( fr, measurement, option = "image" )

Implemented in Python.

Input

fr Image Gray-scale (uint8 or uint16) image.

Labeled image.
measurement String

Choice from 'AREA', 'CENTROID', or 'BOUNDINGBOX'.
option String

Output format: 'image': results as a binary image; 'data': results a column vector of measurements (double).

Default: "image"

Output

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

Description

Take measurements from the labeled image fr. The measurements are: area, centroid, or bounding rectangle. The parameter option controls the output format: 'IMAGE': the result is an image; 'DATA': the result is a double column vector with the measurement for each blob. The region with label zero is not measured as it is normally the background. The measurement of region with label 1 appears at the first row of the output.

Source Code

def mmblob(fr, measurement, option="image"):
    from Numeric import NewAxis, ravel, zeros, sum, nonzero, sometrue, array
    from string import upper
    measurement = upper(measurement)
    option      = upper(option)
    if len(fr.shape) == 1: fr = fr[NewAxis,:]
    n = max(ravel(fr))
    if option == 'DATA': y = []
    else               : y = zeros(fr.shape)
    if measurement == 'AREA':
        for i in range(1,n+1):
            aux  = fr==i
            area = sum(ravel(aux))
            if option == 'DATA': y.append(area)
            else               : y = y + area*aux
    elif measurement == 'CENTROID':
        for i in range(1,n+1):
            aux  = fr==i
            ind  = nonzero(ravel(aux))
            indx = ind / fr.shape[1]
            indy = ind % fr.shape[1]
            centroid = [sum(indx)/len(ind), sum(indy)/len(ind)]
            if option == 'DATA': y.append([centroid[1],centroid[0]])
            else               : y[centroid] = 1
    elif measurement == 'BOUNDINGBOX':
        for i in range(1,n+1):
            aux = fr==i
            aux1, aux2 = sometrue(aux,0), sometrue(aux,1)
            col , row  = nonzero(aux1)  , nonzero(aux2)
            if option == 'DATA': y.append([col[0],row[0],col[-1],row[-1]])
            else:
                y[row[0]:row[-1],col[0] ] = 1
                y[row[0]:row[-1],col[-1]] = 1
                y[row[0], col[0]:col[-1]] = 1
                y[row[-1],col[0]:col[-1]] = 1
    else:
        print "Measurement option should be 'AREA','CENTROID', or 'BOUNDINGBOX'."
    if option == 'DATA':
        y = array(y)
        if len(y.shape) == 1: y = y[:,NewAxis]
    return y

See also

mmlabel Label a binary image.
mmlabelflat Label the flat zones of gray-scale images.
mmstats Find global image statistics.
mmdrawv Superpose points, rectangles and lines on an image. (replaces mmdraw)
[mmlabel] [Up] [mmlabelflat] Python
Copyright (c) 2003, Roberto A. Lotufo, UNICAMP-University of Campinas; Rubens C. Machado, CenPRA-Renato Archer Research Center.