Complement of an Image using loop

how can I complement an Image by loop like this:

Answer 1

[darova]

Use this trick

for i = 1:m    % rows
    for j = 1: round(n/m*(m-i+1))    % columns
        I(i,j) = original;
    end
    for j = round(n/m*(m-i+1)):n    % columns
        I(i,j) = modificated;
    end
end

[Sadeq Ebrahimi]

Thanks for for the answer!

I used your trick:

I=imread('4.jpg');

[m,n]=size(I)

for i = 1:m % rows

for j = 1: round(n/m*(m-i+1)) % columns

I(i,j) = original;

%I = I(i,j);

end

for j = round(n/m*(m-i+1)):n % columns

I(i,j) = modificated;

% imcomplement(I) = I(i,j);

end

end

figure(1),imshow(I);

but the output is like this:

[darova]

Can'b believe. HOw is this possible?