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From: shilpa khinvasara on 4 Aug 2010 05:59
sir i am trying to write the following code to find the mean of quantized image
in this code i am replicating the sides,but there i some error

[m n]=size(q);

% We need to be able to apply MEAN filter at the boundary pixels.
% The easiest way to handle this is to set up a matrix A2 that has
% the original image A in the center and copies the adjacent
% pixel value around the edges.

k = 3; % How far we need to extend border.
A2 = zeros(m+2*k,n+2*k);
A2(k+1:m+k,k+1:n+k) = q; % Original image in center.

% Extend border pixels.
% Handle the 4 corners first.
A2(1:k,1:k) = q(1,1); % Upper left corner.
A2(1:k,n+k+1:n+2*k) = q(1,n); % Upper right corner.
A2(m+k+1:m+2*k,n+k+1:n+2*k) = q(m,n); % Lower right corner.
A2(m+k+1:m+2*k,1:k) = q(m,1); % Lower left corner.

% To handle the sides, we need to copy 1 row/column at a time.
for i = 1:k
A2(i,k+1:n+k) = q(1,1:n); % Upper.
A2(k+1:m+k,n+k+i) = q(1:m,n); % Right.
A2(m+k+i,k+1:n+k) = q(m,1:n); % Lower.
A2(k+1:m+k,i) = q(1:m,1); % Left.
end;

q=double(q);
y(1,: )=q(1,: );
y(1:166,1)=q(1:166,1);
y(166,: )=q(166,: );
y(1:166,359)=q(1:166,359);



for k=1:3
for j=1:3
y(k,j)=(x(k+1,j+1)+x(k,j+1)+....
x(k+1,j+1)+x(k-1,j)+x(k,j)+....
x(k+1,j)+x(k-1,j-1)+x(k,j-1)+....
x(k+1,j-1))*(1/9);
end
end



figure;
hist(y(:),max(y(:)));
From: ImageAnalyst on 4 Aug 2010 09:45
Why are you enlarging the image by replicating the sides? That is not
necessary to get the mean of the image. You can just do
meanOfImage = mean(q(:));
or
meanOfImage = mean2(q);

If you want a local mean, you can use conv2

blurredImage = conv2(q, ones(3,3)/9, 'same');
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