Summation of specific range of 2d array

Question

Meenal Shah 2020-5-12

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/524819-summation-of-specific-range-of-2d-array

编辑： Meenal Shah 2020-5-13

采纳的回答： Mehmed Saad

在 MATLAB Online 中打开

I have a grayscale image image named tumour.

I need to find the area where the intensity is greater than 0.

I have another variable outline showing the outline of original image.

G1 is an empty array.

To find it properly, I have used this code:

for i=1:200
    for j=1:200
        if((outline(i,j)>0) && sum(sum(tumor(i-5,j-5),tumor(i+5,j+5)))>0)
            G1(i,j)=255;
        end
    end
end

I want to get the outline of only the tumour.

However, I am getting this error (in the sum() part) and I am unable to solve it:

Error using sum
Dimension argument must be a positive integer scalar, a vector of unique positive integers, or 'all'.

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Answer 1

Mehmed Saad 2020-5-12

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https://ww2.mathworks.cn/matlabcentral/answers/524819-summation-of-specific-range-of-2d-array#answer_431950

编辑：Mehmed Saad 2020-5-12

在 MATLAB Online 中打开

I donot understand what you are trying to do in the code. There are much simpler ways to do it.

By looking in your code i think the error is occuring because your for loop index starts from i=1 and ends at i= 200. When you access i-5 or j-5 it will give error because you are indexing negative values to tumor. SImilarly when your loop reaches end it will try to access 200+5 which is out of bound. So run you for loop from

i=1+5:200-5

&

j=1+5:200-5

Edit:

(tumor(i-5,j-5),tumor(i+5,j+5))

and i think what you are intended to do in this line is accessings tumor's i-5th to i+5th index and j-5th to j+5th index( i.e. total 11x11 elements) . AM i right?