how to sum all pixel within a specific distance from each pixel?

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Waseem Farooq 2019-10-14

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编辑： Shivam Prasad 2019-11-5

Hello everyone, I am trying this concept that the code goes through each pixel of an image and sum all the pixel values(to take a mean value then) in a specific distance (2lambda where lambda = 4) from that pixel. this should be done for all the pixels .

Thank you everyone for your response. let me explain it abit.

img_out(:,:,n) = conv2(img_in, gb,'same');

img_out is the one i want to work with now. i am gonna write some comments about what i want to achieve now.

% calculate the number of pixels in distance limit of 2 lambda to 12 lambbda(lammba is the wavelength of gabor filter but for simplicity here just consider it 4)

% to explain the above comment a bit more i have to start from pixel 1 and will go through all the pixels till the end.

e-g for pixel 1, pixel 1 will be the target pixel and we will have to sum all the pixel values of the neighbouring pixels in the distance of 2lambda to 12 lambda.

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Shivam Prasad 2019-10-17

编辑：Shivam Prasad 2019-10-17

Hi Waseem,

Can you tell me what you mean by :-

"then) in a specific distance (2lambda where lambda = 4) from that pixel. this should be done for all the pixels ."

KALYAN ACHARJYA 2019-10-17

"... in a specific distance"

Distance from??....to each pixels ..

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Answer 1

Walter Roberson 2019-10-17

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conv2 with a mask that is 1 for each pixel to be considered. The exact pattern will depend on which distance measurement you want to use. See strel() to construct some of the common ones.

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Shivam Prasad 2019-10-18

编辑：Shivam Prasad 2019-10-18

Hi Waseem,

I understand that the value of lambda remains the same throughout the operation. However, the size of a pixel is not fixed. It is dependent on resolution of the output screen.

Can you change the distance metric (pixels) to something else?

Also, please specify the unit of lambda.

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Answer 2

Shivam Prasad 2019-10-18

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Hi Waseem,

Check if this works. I have made some changes to your code.

array=[1.0,5.0,25.0,27.0,35.0,38.0,41.0,50.0];
matchingpixels= zeros(length(array));
thresholddis=4.0;
for i=1:length(array)
    fprintf('Pixels found closer to %i =',i);
    currentPos=array(i);   
    sum=0;
    
    for j=1:length(array)
        if j~=i
            otherPos=array(j); 
            if  abs(currentPos-otherPos)<thresholddis
                fprintf('%i ',j);
                sum = sum+otherPos;
            end
        end  
    end
    fprintf('\nSum of pixel values = %i\n',sum);
end

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Shivam Prasad 2019-10-21

编辑：Shivam Prasad 2019-11-5

It's difficult to understand the code at a go. There is no reference to variables like tEnd. I suggest you to go through the logic which I have implemented in the sample code and make changes in your real code accordingly.

The idea is to use a nested for loop. Both the loops will iterate through all the neutrons. Calculate the distance between the neurons from the outer and inner loop. If this distance is between 2 and 12 lambda, output these neurons, and also add this distance in a variable SUM initialized to zero just before the inner loop starts. Output the value of the variable SUM outside the inner loop.

Waseem Farooq 2019-10-21