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MATLAB PROGRAM : 2D MEDIAN FILTERING FOR SALT AND PEPPER NOISE WITHOUT USING medfilt2 FUNCTION

MEDIAN FILTER:

In digital Image processing, removing the noise is one of the preprocessing techniques.
The image noise may be termed as random variation of brightness or color information.
There are various types of image noise. Here a matlab program to remove 'salt and pepper noise' using median filtering is given.
 The random occurrence of black and white pixels is ‘salt and pepper noise’.

The procedural steps for 2D median filtering:


Learn how to pad with zeros using MATLAB built_in function padarray.

FLOW CHART:


MATLAB CODE:

%READ AN 2D IMAGE
A=imread('zebra.jpg');
title('IMAGE WITH SALT AND PEPPER NOISE');
figure,imshow(A);

%PAD THE MATRIX WITH ZEROS ON ALL SIDES
modifyA=zeros(size(A)+2);
B=zeros(size(A));

%COPY THE ORIGINAL IMAGE MATRIX TO THE PADDED MATRIX
        for x=1:size(A,1)
            for y=1:size(A,2)
                modifyA(x+1,y+1)=A(x,y);
            end
        end
      %LET THE WINDOW BE AN ARRAY
      %STORE THE 3-by-3 NEIGHBOUR VALUES IN THE ARRAY
      %SORT AND FIND THE MIDDLE ELEMENT
       
for i= 1:size(modifyA,1)-2
    for j=1:size(modifyA,2)-2
        window=zeros(9,1);
        inc=1;
        for x=1:3
            for y=1:3
                window(inc)=modifyA(i+x-1,j+y-1);
                inc=inc+1;
            end
        end
       
        med=sort(window);
        %PLACE THE MEDIAN ELEMENT IN THE OUTPUT MATRIX
        B(i,j)=med(5);
       
    end
end
%CONVERT THE OUTPUT MATRIX TO 0-255 RANGE IMAGE TYPE
B=uint8(B);
title('IMAGE AFTER MEDIAN FILTERING');
figure,imshow(B);












Learn how to add 'salt and pepper noise to an image'.Median filtering preserves the image without getting blurred. Median filtering is done on an image matrix by   finding the median of the neighborhood pixels by using a window that slides pixel by pixel.


  

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24 comments:

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Phongthorn.jant said... Reply to comment

thank you so much for project lol

jeena said... Reply to comment

thanks a lot for this code

punya said... Reply to comment

great, thankx a lot, wht can i say, amazing

Pooja Dixit said... Reply to comment

thanks for this helpful code...

annah said... Reply to comment

thank you..it helps alot.. :)

HANEE said... Reply to comment

great job but why is my image become red after the MEDIAN FILTERING???

Aaron Angel said... Reply to comment

@HANEE

Kindly check whether the image is 2D or RGB image. If the image is RGB then convert it into grayscale and proceed.

HANEE said... Reply to comment

it worked perfectly with Gaussian Filter but not with Median Filter(image becomes red), i'm now trying with other images to see whether it is a image problem or what..

Awanish Shukla said... Reply to comment

thanks for this usefull code........
can we selection direction in a window ? if yes how is it possible ? actually i m thinking to preserve edges of image.......

Christian Andreoli said... Reply to comment

thanks

Christian Andreoli said... Reply to comment

I ve a problem with the Median Filter. The image becomes red.
Somebody can help me with this problem?

Christian Andreoli said... Reply to comment

I ve also the problem that the picture becomes red with the Median Filter . Can somebody help? Thank you a lot

Christian Andreoli said... Reply to comment


Do you have also an Matlab Code for the Gauss filter?

I didn t find / see one
Thanks

regrads,

CHristian

Deniz Eraslan said... Reply to comment

thanks. this is really helpful

Kalpana Sekar said... Reply to comment

whether any functions will change wen v change the version of matlab

radhi ka said... Reply to comment

hi can you give the same code for fuzzy median filter pa

sajid khan said... Reply to comment

nice work

sajid khan said... Reply to comment

Can someone code for Wiener Filter please for gray scale image

Janardhan Mopada said... Reply to comment

I ve also the problem that the picture becomes red with the Median Filter . Can somebody help? Thank you a lot

Aaron Angel said... Reply to comment

@Janardhan Mopada

Is your input Image RGB? if so, convert it to grayscale and proceed.

kassambe said... Reply to comment

do you have a code for contour detection with many algorithm?

tememe said... Reply to comment

thank you very useful

Vivek Tiwari said... Reply to comment

Anybody can provide me the code of the 'Noise Reduction By Fuzzy Image Filtering''.

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