L=imread('krakow.jpg');
 figure(1); imshow(L);
L1=im2double(rgb2gray(L));
 figure(2);imshow(L1);
 L2=imnoise(L1,"salt & pepper",0.1);
 figure(3); imshow(L2)
 Kernel1=ones(3);
L3=filter2(Kernel1,L2);
 L3=mat2gray(L3);
 figure(4); imshow(L3);