I am trying to display an image of covariance(covariance map) using this code but I receive a false result , please would you help me with this (I need this for my master degree)

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chaima kadess 2018-9-11

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/418550-i-am-trying-to-display-an-image-of-covariance-covariance-map-using-this-code-but-i-receive-a-false

评论： chaima kadess 2018-9-17

image.png

clc
close all
clear all
img = imread('C:\test\image\image1.jpg'); %lire l'image de reference
I = rgb2gray(img); %convertir en niveau de gris
I1 = medfilt2(I, [5 5]);
C=imcrop(I1, [18.5 29.5 31 29]); %imcrop an ROI(left ventricular)
[m,n]=size(C);
for i=1:m
  for j=1:n
    for num=1:16
       file=['image', num2str(num),'.','jpg'];
       im = im2double(imread(fullfile('C:\test\image', file)));
            im = rgb2gray(im); %convertir en niveau de gris
          I2 = medfilt2(im, [5 5]);
          C=imcrop(I2,[18.5 29.5 31 29]); 
      a(i,j)= C(i,j); 
  C1 = imcrop(C, [20.5 16.5 5 4]); %ROI2 inside the first ROI
  [m1,n1]= size(C1);
      end
  mua(i,j)=((1/16)*(sum(C(i,j))));  
    end
  end
for num=1:16
    for i=1:m1
      for j=1:n1
        a1(i,j)=C1(i,j);
      end
    end
AR(num)=((1/(m1*n1))*(a1(i,j))); %%%%%%%%%%%%
end
% % 
for i=1:m1
        for j=1:n1
            muar =((1/16)*sum(AR)); 
        end
end
for i=1:m1
        for j=1:n1
            for num=1:16
            cov(i,j) = sum((a1(i,j) - mua(i,j))*(AR - muar));
            end
   covtot(i,j) = ((1/16)*sum(cov(i,j)));
          end
  end
figure(1);
imagesc(covtot),title('image de covariance'),
colorbar, colormap(jet);

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chaima kadess 2018-9-11

yes it is

chaima kadess 2018-9-11

no ,I am working with a sequence of 16 images and I want to display finally one image of covariance from this 16 images.

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回答（1 个）

Walter Roberson 2018-9-11

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在 MATLAB Online 中打开

You should replace a bunch of your code.

    numimg = 16;
    mut = zeros(m, n);
    for num = 1:numimg
       file = ['image', num2str(num),'.','jpg'];
       im = im2double(imread(fullfile('C:\test\image', file)));
       im = rgb2gray(im); %convertir en niveau de gris
       I2 = medfilt2(im, [5 5]);
       C = imcrop(I2,[18.5 29.5 31 29]); 
       mut = mut + C;
       C1 = imcrop(C, [20.5 16.5 5 4]); %ROI2 inside the first ROI
       AR(num) = mean2(C1);
    end
   mua = mut ./ numimg;

I had to make an assumption here about what you were calculating with mua.

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Walter Roberson 2018-9-12

If it is the average of a(i,j) over all of the images, then that is what I have the code calculate.

chaima kadess 2018-9-17

thank you for responding me , but unfortunately it doesn't works , I have a sequence of 16 cardiac images ,the first image will be taken as a reference(c1(i,j)) following this equation : cov(i,j)=(1/T)*((C1(i,j)-mua(i,j))*(AR-muar)) where T is the frame number and mua(i,j) is the mean of the (i j) pixel value in the image series and AR is the mean value of all pixels located in the region of reference and muar is the mean value of the references series.so i am looking to display an image of the calculated covariance . hopefully you can help me mrs.

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