Mahotas – Image Ellipse Axes

In this article we will see how we can get the image ellipse axes in mahotas. Ellipse exes are parameters of the image ellipse, parameters of the constant intensity ellipse with the same mass and second-order moments as the original image.
For this tutorial we will use ‘lena’ image, below is the command to load the lena image 

mahotas.demos.load('lena')

Below is the lena image 

In order to do this we will use mahotas.features.ellipse_axes method
Syntax : mahotas.features.ellipse_axes(img)
Argument : It takes image object as argument
Return : It returns two float values 

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
import matplotlib.pyplot as plt

# loading image
img = mahotas.demos.load('lena')

# filtering image
img = img.max(2)

print("Image")

# showing image
imshow(img)
show()

# computing Parameters of the ‘image ellipse’
semimajor, semiminor = mahotas.features.ellipse_axes(img)


# showing value
print("Semi Major Exes : " + str(semimajor))
print("Semi Minor Exes : " + str(semiminor))

Output :

Image

Semi Major Exes : 295.60277400592844
Semi Minor Exes : 295.60277400592844

Another example 

Python3

# importing required libraries
import mahotas
import numpy as np
from pylab import gray, imshow, show
import os
import matplotlib.pyplot as plt

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


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

print("Image")

# showing image
imshow(img)
show()
# computing Parameters of the ‘image ellipse’
semimajor, semiminor = mahotas.features.ellipse_axes(img)


# showing value
print("Semi Major Exes : " + str(semimajor))
print("Semi Minor Exes : " + str(semiminor))

Output :

Image

Semi Major Exes : 508.79612573247636
Semi Minor Exes : 308.5809619544451