Mahotas – Euler number of Image

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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

Python3

# importing required libraries
import mahotas
import mahotas.demos
from pylab import gray, imshow, show
import numpy as np
   
# loading image
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 Method")
 
# 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))

Output :

Image threshold using Otsu Method

Euler Number of Image : 54.25

Another example

Python3

# importing required libraries
import mahotas
import numpy as np
from pylab import gray, imshow, show
import os
  
# loading image
img = mahotas.imread('dog_image.png')
 
 
# filtering 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 Method")
   
# showing image
imshow(img)
show()
 
 
# euler number of image of image
euler = mahotas.euler(img)
 
print("Euler Number of Image : " + str(euler))