sum the matrix 3x3 and looping

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renuka
renuka on 28 Feb 2014
Edited: renuka on 2 Mar 2014
how to calculate the total of overlap region 3x3 of a matrix and include loop function as it continue to calculate row by row and column by column.
  2 Comments
the cyclist
the cyclist on 28 Feb 2014
Edited: the cyclist on 28 Feb 2014
This is not even close to detailed enough to help you. For starters, what does "overlap region" mean?
Please remember, we only know what you tell us about your problem.
renuka
renuka on 1 Mar 2014
Edited: renuka on 2 Mar 2014
sorry, it suppose to be like this. i have the code to calculate the sum for the matrix, but dun't know how to do the looping part.
t=rand(6,6)
total = 0;
for i=1:3
for j=1:3
total = total + t(i,j)
end
end

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Accepted Answer

Image Analyst
Image Analyst on 1 Mar 2014
That can be done very simply with imfilter() or conv2():
outputArray = conv2(double(inputArray), ones(3), 'same');
Every element (pixel) in the output array (image) will be the sum of input elements (pixels) in the sliding window.
  7 Comments
Image Analyst
Image Analyst on 2 Mar 2014
Edited: Image Analyst on 2 Mar 2014
x = [1 2 3 4;5 6 7 8;9 10 11 12;13 14 15 16]
theSums = conv2(x, ones(3), 'valid')
Result:
theSums =
54 63
90 99
As you can see, you forgot one sum. Please mark the answer as Accepted if we're done here. Thanks.
renuka
renuka on 2 Mar 2014
thank you very much.

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