standard deviation of image

3 次查看（过去 30 天）
Hassan
Hassan 2011-12-9
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

请先登录，再回答此问题。

回答（2 个）

Sean de Wolski
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)
  4 个评论
显示 2更早的评论
Hassan
Hassan 2011-12-10
Thanks Sean for the comment. As I said I have 2 images, image 1 is a 3-dimensional image and image 2 is a categorised 2-dimensional image with values 1 to 7. I want to find the standard deviation of the pixels values from image 1 that has a value of 1 (and then 2, 3,4 ,..,7) in image 2.
Hassan
Hassan 2011-12-10
Sorry guys for not desribing the problem clearly. You are right Walter 'Each of the areas in the 2D image acts as a mask to be applied to the 3D image.'
thats right Image Analyst.

请先登录，再进行评论。

Image Analyst
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.
  3 个评论
显示 1更早的评论
Image Analyst
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
Hassan
Hassan 2011-12-10
I couldnt run the code. I got the following error messageç
??? Error using ==> bwlabel
Too many input arguments.
I think binary image should be the 2'dimensional categorized image and gray image should be the 3'dimensional image.
[labeledImage, numberOfBlobs] = bwlabel(image 2, image 1, 'PixelValues');
sd = zeros(1, numberOfBlobs);
for k = 1 : numberOfBlobs
pixelValues = [STATS(k).PixelValues];
sd(k) = std(pixelValues(:)); % StDev of kth blob
end

请先登录，再进行评论。

类别

在 Help Center 和 File Exchange 中查找有关 Image Segmentation and Analysis 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by