In this article we will see how we can apply rank filter on image in mahotas. The rank filter, especially filters isolated pixels out, whose intensity differs greatly from that of its immediate neighborhood. Large areas with constant intensity values adjacent to these pixels, as well as edges, are retained after this filter has been used.
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.rank_filter
methodSyntax : mahotas.rank_filter(img, neighbour, rank)
Argument : It takes image object and two integer as argument
Return : It returns image object
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
# importing required libraries import mahotas import mahotas.demos from pylab import gray, imshow, show import numpy as np import matplotlib.pyplot as plt # loading iamge img = mahotas.demos.load( 'lena' ) # filtering image img = img. max ( 2 ) print ( "Image" ) # showing image imshow(img) show() # neighbour pixel neighbour = 3 # rank rank = 2 # applaying rank filter new_img = mahotas.rank_filter(img, neighbour, rank) # showing image print ( "Rank Filter" ) imshow(new_img) show() |
Output :
Image
Rank Filter
Another example
# importing required libraries import mahotas import numpy as np from pylab import gray, imshow, show import os import matplotlib.pyplot as plt # loading iamge img = mahotas.imread( 'dog_image.png' ) # fltering image img = img[:, :, 0 ] print ( "Image" ) # showing image imshow(img) show() # neighbour pixel neighbour = 3 # rank rank = 2 # applaying rank filter new_img = mahotas.rank_filter(img, neighbour, rank) # showing image print ( "Rank Filter" ) imshow(new_img) show() |
Output :
Image
Rank Filter
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