Mahotas – Match template to image exactly

In this article we will see how we can match a template with the image in mahotas. By matching templates we can find the specific location or things in a image with the help of structure we want to find.

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.find method

Syntax : mahotas.find(img, template) 

Argument : It takes image object and template as argument

Return : It returns boolean ndarray

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")

# showing image
imshow(img)
show()

# template
template = np.array([
        [0, 1, 1],
        [0, 1, 1],
        [0, 1, 1]], bool)


# finding template in the image
new_img = mahotas.find(img, template)

print("Image with only templates")
# showing new image
imshow(new_img)
show()

Output :

Image threshold using Otsu Method

Image with only templates

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()

# template
template = np.array([
        [0, 1, 1],
        [0, 1, 1],
        [0, 1, 1]], bool)


# finding template in the image
new_img = mahotas.find(img, template)

print("Image with only templates")
# showing new image
imshow(new_img)
show()

Output :

Image threshold using Otsu Method

Image with only templates