MATLAB Answers

image processing problem in Salt and Pepper noise

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Mohammad abu aqoulah
Mohammad abu aqoulah on 1 Jun 2020
Answered: Image Analyst on 1 Jun 2020
i try to add Salt and Pepper noise after that try to use median filter to denoise it in this code but has a problem
code ;
I = imread('PicQ1.png');
figure ,imshow(I)
J = imnoise(I,'salt & pepper',0.05);
figure ,imshow(J)
M = medfilt2(J);
imshowpair(J,M,'montage')
--------------------------------------------
the proplem shown in pic attached

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Answers (2)

Sugar Daddy
Sugar Daddy on 1 Jun 2020
Edited: Sugar Daddy on 1 Jun 2020
You are feeding a coloured image which is three dimensional ( RGB) while medfilt2 needs 2D data.
For example
I = imread('cameraman.tif');%default image
figure ,imshow(I);
J = imnoise(I,'salt & pepper',0.05);
M = medfilt2(J);% Now this will work because I is a gray scaled image
imshowpair(J,M,'montage')
Either change your rgb image to grayscale or apply medfilt2 on all three colours sequentialy
see the answer of image analyst below about how to apply median filter on coloured image

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Mohammad abu aqoulah
Mohammad abu aqoulah on 1 Jun 2020
i try this code and work
clc
clear all
close all
I = imread('PicQ3.jpg');
subplot(2,2,1); imshow(I),title ('Original image')
J = imnoise(I,'salt & pepper',0.05);
subplot(2,2,2);imshow(J), title('Salt and Pepper" noise')
for (i=1:3)
M(:,:,i) = medfilt2(J(:,:,i),[3,3]);
end
subplot(2,2,3);imshow(M),title('after filtering')
Sugar Daddy
Sugar Daddy on 1 Jun 2020
If your issue is resolved please accept the answer

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Image Analyst
Image Analyst on 1 Jun 2020
A better method is to use a modified median filter where you only replace the noise pixels with the median, not ALL pixels. This will prevent blurring and shape changing.

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