standard deviation of image
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I have a 3-dimensional image (image1) and a 2-dimensional image (image2) with values from 1 to 7 and want to find the standard deviation for specific values. I'm using the following code to calculate the mean value but dont know how to calculate the standard deviation. Any suggestion please?
for i=1:3
x=image1(:,:,i)
for j=1:7
L = bwlabel(image2==j);
STATS = regionprops(L,x,'MeanIntensity','Area','PixelValues');
n_stats = size(STATS,1);
area_=zeros(n_stats,1);
mean_=zeros(n_stats,1);
[m1,n1] = find(cat(1,STATS.Area) >=5);
for ii=1:n_stats
mean_(ii)=STATS(ii,:).MeanIntensity;
end
mean1=mean_(m1);
mean2(j,i)=mean(mean1);
end
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回答(2 个)
Sean de Wolski
2011-12-9
You can use regionprops to calculate the various fields requested of each label in a label image, e.g.:
A = uint8(rand(10)*10); %random label image
STATS = regionprops(A,'area');
areas = [STATS(:).Area]
And I don't understand what you want the standard deviation of. If youu want it of all objects with the same value, won't it be zero? Clarify your goal, I guess. (and look at stdfilt)
Image Analyst
2011-12-9
I don't have MATLAB on this computer so I can't test but I believe it would be something like
pixelValues = [STATS(k).PixelValues];
sd = std(pixelValues(:)); % StDev of kth blob
or something like that.
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Image Analyst
2011-12-10
That's the kth region. You'd have it in a loop over all k, all possible blob numbers, like
[labeledImage, numberOfBlobs] = bwlabel(binaryImage, grayImage, 'PixelValues');
sd = zeros(1, numberOfBlobs);
for k = 1 : numberOfBlobs
pixelValues = [STATS(k).PixelValues];
sd(k) = std(pixelValues(:)); % StDev of kth blob
end
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