Mahotas – Getting Labeled Max Array

In this article we will see how we can obtain the labeled max array of the in mahotas. Labeled images are integer images where the values correspond to different regions. I.e., region 1 is all of the pixels which have value 1, region two is the pixels with value 2, and so on. By convention, region 0 is the background and often handled differently. We can create a labelled region with the help of mahotas.label method.
We can get the size of each region with the help of mahotas.label_size method, this size is measured simply as the number of pixels in each region. We can instead measure the total weight in each area.
In order to do this we will use mahotas.labeled.labeled_max method 

Syntax : mahotas.labeled.labeled_max(array, labeled_img)
Argument : It takes two numpy.ndarray object as argument i.e random array of region shape and labeled region
Return : It returns ndarray of numpy.float64 values 

Example 1:

Python3

# importing required libraries
import mahotas
import numpy as np
from pylab import imshow, show

# creating region
# numpy.ndarray
regions = np.zeros((10, 10), bool)

# setting 1 value to the region
regions[:3, :3] = 1
regions[6:, 6:] = 1

# getting labeled function
labeled, nr_objects = mahotas.label(regions)

# showing the image with interpolation = 'nearest'
imshow(labeled, interpolation ='nearest')
show()


# random array of region shapes
array = np.random.random_sample(regions.shape)

# getting labeled max array
l_array = mahotas.labeled.labeled_max(array, labeled)

print("Labeled Max array :")
# printing the  values
for i in range(len(l_array)):
    print("Region " + str(i) + " : " + str(l_array[i]))

Output :

Labeled Max array :
Region 0 : 0.9980513142322492
Region 1 : 0.624390200202312
Region 2 : 0.9210927640926101

Example 2:

Python3

# importing required libraries
import numpy as np
import mahotas
from pylab import imshow, show

# loading image
img = mahotas.imread('dog_image.png')

# filtering the image
img = img[:, :, 0]

# setting gaussian filter
gaussian = mahotas.gaussian_filter(img, 15)

# setting threshold value
gaussian = (gaussian > gaussian.mean())

# creating a labeled image
labeled, n_nucleus = mahotas.label(gaussian)

print("Labelled Image")
# showing the gaussian filter
imshow(labeled)
show()


# random array of region shapes
array = np.random.random_sample(labeled.shape)

# getting labeled max array
l_array = mahotas.labeled.labeled_max(array, labeled)

print("Labeled Max array :")
# printing the  values
for i in range(len(l_array)):
    print("Region " + str(i) + " : " + str(l_array[i]))

Output :

Labeled Max array :
Region 0 : 0.9999995478951564
Region 1 : 0.9999944289534851
Region 2 : 0.999718434740755
Region 3 : 0.9996236088210476
Region 4 : 0.9861670123032187