How to change a 3x3 median filter to 5x5?

My code works, but i need a 5x5 filter not 3x3. I tried to alter the code to get the 5x5 but keep getting an error

%% 2. Median Filter
%READ IMAGE
sad1=imread('sadimg.bmp');
figure,imshow(sad1)
title('IMAGE WITH NOISE');

%PAD THE MATRIX WITH ZEROS ON ALL SIDES
median_filt=zeros(size(sad1)+2);
re_sad1=zeros(size(sad1));

%COPY THE ORIGINAL IMAGE MATRIX TO THE PADDED MATRIX
        for x=1:size(sad1,1)
            for y=1:size(sad1,2)
                median_filt(x+1,y+1)=sad1(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(median_filt,1)-2
    for j=1:size(median_filt,2)-2
        window=zeros(9,1);
        inc=1;
        for x=1:3
            for y=1:3
                window(inc)=median_filt(i+x-1,j+y-1);
                inc=inc+1;
            end
        end
       
        med=sort(window);
        %PLACE THE MEDIAN ELEMENT IN THE OUTPUT MATRIX
        re_sad1(i,j)=med(5);
       
    end
end
%CONVERT THE OUTPUT MATRIX TO 0-255 RANGE IMAGE TYPE
re_sad1=uint8(re_sad1);
title('IMAGE AFTER MEDIAN FILTERING');
figure,imshow(re_sad1)

this was my attempt but i get the error : "ndex exceeds the number of array elements (25)."

%% 2. Median Filter
%READ IMAGE
sad1=imread('sadimg.bmp');

%PAD THE MATRIX WITH ZEROS ON ALL SIDES
median_filt=zeros(size(sad1)+2);
re_sad1=zeros(size(sad1));

%COPY THE ORIGINAL IMAGE MATRIX TO THE PADDED MATRIX
        for x=1:size(sad1,1)
            for y=1:size(sad1,2)
                median_filt(x+1,y+1)=sad1(x,y);
            end
        end
        
%LET THE WINDOW BE AN ARRAY
%STORE THE 5-by-5 NEIGHBOUR VALUES IN THE ARRAY
%SORT AND FIND THE MIDDLE ELEMENT       
for i= 1:size(median_filt,1)-3
    for j=1:size(median_filt,2)-3
        window=zeros(25,1);
        inc=1;
        for x=1:5
            for y=1:5
                window(inc)=median_filt(i+x-1,j+y-1);
                inc=inc+1;
            end
        end
       
        med=sort(window);
        %PLACE THE MEDIAN ELEMENT IN THE OUTPUT MATRIX
        re_sad1(i,j)=med(175);
       
    end
end
%CONVERT THE OUTPUT MATRIX TO 0-255 RANGE IMAGE TYPE
re_sad1=uint8(re_sad1);

figure
subplot(2,1,1);
imshow(sad1)
title('IMAGE WITH NOISE');
subplot(2,1,2);
imshow(re_sad1)
title('IMAGE AFTER MEDIAN FILTERING');

[Rena Berman]

(Answers Dev) Restored edit

[Rahmi]

3x3 that's mean 3 layer or different?

[DGM]

It's a local median filter that works in a 3x3 window on a 2D array.

Answer 1

[DGM]

Start by simplifying:

% 2. Median Filter
%READ IMAGE
inpict = imread('sadimg.bmp');
%imshow(inpict)
%title('IMAGE WITH NOISE');

% make things parametric instead of hard-coding everything
filtersize = [5 5]; % or whatever size

% PAD THE MATRIX WITH ZEROS ON ALL SIDES
padsize = floor(filtersize/2);
paddedimage = padarray(inpict,padsize,0,'both');

s0 = size(inpict);
outpict = zeros(s0,class(inpict));
os = filtersize-1; 

for m = 1:s0(1)
    for n = 1:s0(2)
        %PLACE THE MEDIAN ELEMENT IN THE OUTPUT MATRIX
        sample = paddedimage(m:(m+os(1)),n:(n+os(2)));
        outpict(m,n) = median(sample(:)); % what's wrong with median()?
    end
end

% test the output against existing tools
referenceimage = medfilt2(inpict,filtersize);
immse(outpict,referenceimage) % show that this filter behaves the same as medfilt2()

title('IMAGE AFTER MEDIAN FILTERING');
imshow(outpict)