Mahotas – Euler number of Image

In this article we will see how we can get the euler number of the image in mahotas. The Euler number is a measure of the topology of an image. It is defined as the total number of objects in the image minus the number of holes in those objects. You can use either 4- or 8-connected neighborhoods.

In this tutorial we will use “lena” image, below is the command to load it.

mahotas.demos.load('lena')

Below is the lena image

In order to do this we will use mahotas.euler method



Syntax : mahotas.euler(img)

Argument : It takes image object as argument

Return : It returns integer

Note : Input image should be filtered or should be loaded as grey

In order to filter the image we will take the image object which is numpy.ndarray and filter it with the help of indexing, below is the command to do this

image = image[:, :, 0]

Below is the implementation

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# importing required libraries
import mahotas
import mahotas.demos
from pylab import gray, imshow, show
import numpy as np
    
# loading iamge
img = mahotas.demos.load('lena')
  
  
    
# filtering image
img = img.max(2)
  
# otsu method
T_otsu = mahotas.otsu(img)   
    
# image values should be greater than otsu value
img = img > T_otsu
    
print("Image threshold using Otsu Mehtod")
  
# creating a labeled image
marker, n_nucleus = mahotas.label(img)
    
# showing image
imshow(img)
show()
  
  
# euler number of image of image
euler = mahotas.euler(img)
  
print("Euler Number of Image : " + str(euler))

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Output :

Image threshold using Otsu Mehtod

Euler Number of Image : 54.25

Another example

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# importing required libraries
import mahotas
import numpy as np
from pylab import gray, imshow, show
import os
   
# loading iamge
img = mahotas.imread('dog_image.png')
  
  
# fltering image
img = img[:, :, 0]
    
# otsu method
T_otsu = mahotas.otsu(img)   
    
# image values should be greater than otsu value
img = img > T_otsu
    
print("Image threshold using Otsu Mehtod")
    
# showing image
imshow(img)
show()
  
  
# euler number of image of image
euler = mahotas.euler(img)
  
print("Euler Number of Image : " + str(euler))

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Output :

Image threshold using Otsu Mehtod

Euler Number of Image : 76.75



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