# mean filter special matrix apply to image. Salt and pepper noise

7 views (last 30 days)
mustafa karatas on 19 Dec 2021
Commented: mustafa karatas on 5 Jan 2022
How can I apply mean filter like 3x3 square neigboorhod following matrix?
mean4=[0,1,0;1,1,1;0,1,0];
I would like to apply with noise image this method. Here is my code:
figure
imshow(orgim)
saltpeppern = imnoise(orgim,'salt & pepper');
figure
imshow(saltpeppern)

DGM on 20 Dec 2021
Normalize the filter sum and apply it with imfilter().
noisyimg = imnoise(originalimg,'salt & pepper');
fk = [0,1,0;1,1,1;0,1,0]/5; % unit sum
avgfiltimg = imfilter(noisyimg,fk);
imshow(originalimg)
figure; imshow(noisyimg)
figure; imshow(avgfiltimg)
mustafa karatas on 5 Jan 2022
thanks

yanqi liu on 20 Dec 2021
clc; clear all; close all;
mean4=[0,1,0;1,1,1;0,1,0];
% i would like to apply with noise image this method.here is my code;
figure
imshow(orgim)
saltpeppern = imnoise(orgim,'salt & pepper');
figure
imshow(saltpeppern)
% use imfilter
im1 = imfilter(double(saltpeppern), mean4, 'replicate');
% use conv2
im2 = conv2(double(saltpeppern), mean4, 'same');
% use fft
im3 = real(ifft2(fft2(double(saltpeppern)).*fft2(mean4, size(saltpeppern,1), size(saltpeppern,2))));
% display
figure; imshow(im1, []); title('use imfilter');
figure; imshow(im2, []); title('use conv2');
figure; imshow(im3, []); title('use fft');
mustafa karatas on 5 Jan 2022
thanks

Image Analyst on 20 Dec 2021
See my attached salt and pepper demos. It adds noise to the original image, then takes the median filter of the image. Then it identified the location of the noise and replaces only those noise pixels with the median filtered value.
mustafa karatas on 5 Jan 2022
thanks