In this article we will see how we can implement otsu’s method in mahotas. In computer vision and image processing, Otsu’s method, named after Nobuyuki Otsu, is used to perform automatic image thresholding. In the simplest form, the algorithm returns a single intensity threshold that separates pixels into two classes, foreground and background.
In this tutorial we will use “luispedro” image, below is the command to load it.
mahotas.demos.load('luispedro')
Below is the luispedro image
In order to do this we will use mahotas.otsu method
Syntax : mahotas.otsu(image)
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]
Example 1:
Python3
# importing required librariesimport mahotasimport mahotas.demosimport numpy as npfrom pylab import imshow, gray, showfrom os import path# loading the imagephoto = mahotas.demos.load('luispedro')# showing original imageprint("Original Image")imshow(photo)show()# loading image as greyphoto = mahotas.demos.load('luispedro', as_grey = True)# converting image type to unit8# because as_grey returns floating valuesphoto = photo.astype(np.uint8)# otsu methodT_otsu = mahotas.otsu(photo)# printing otsu valueprint("Otsu Method value : " + str(T_otsu))print("Image threshold using Otsu Method")# showing image# image values should be greater than otsu valueimshow(photo > T_otsu)show() |
Output :
Example 2:
Python3
# importing required librariesimport mahotasimport numpy as npfrom pylab import imshow, showimport os# loading imageimg = mahotas.imread('dog_image.png') # setting filter to the imageimg = img[:, :, 0]imshow(img)show()# otsu methodT_otsu = mahotas.otsu(img)# printing otsu valueprint("Otsu Method value : " + str(T_otsu))print("Image threshold using Otsu Method")# showing image# image values should be greater than otsu valueimshow(img > T_otsu)show() |
Output :
