self-defined gaussian kernel

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MatLab

image-processing

I was wondering if anyone could look at this code. I'm trying to do a 3x3 gaussian kernel without using any matlab built-in functions. (Yes I am aware of all the built in functions of gaussian and convolution ie fspecial) the result gives me a white image instead. not sure what's the problem with it.
Thanks.

 clc;

close all;

clear all;





img=imread('image.jpg');

figure,imshow(img);




img2=zeros(size(img)+2);

newImg=zeros(size(img));



for rgb=1:3

        for x=1:size(img,1)

            for y=1:size(img,2)

                img2(x+1,y+1,rgb)=img(x,y,rgb);

            end

        end

end


    for i= 1:size(img2,1)-2

        for j=1:size(img2,2)-2

            window=zeros(9,1);

            inc=1;

            for x=1:3

                for y=1:3

                    window(inc)=img2(i+x-1,j+y-1,rgb);

                    inc=inc+1;

                end

            end


              kernel=[1;2;1;2;4;2;1;2;1];

%             kernel=[0;1;0;1;-4;1;0;1;0];


            med=window.*kernel;

            disp(med);

            med=sum(med);

            med=floor(med);



            newImg(i,j,:)=med;



        end

    end



newImg=uint8(newImg);

figure,imshow(newImg);