std2 ROI
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Hi,
I am looking to calculate the standard deviation of intensity values of a grayscale image.
I do not want to calculate the standard deviation of the entire image, but just a ROI.
I can create a binary mask, but can not see a way of using this to extract the ROI statistics.
Any help would be greatly appreciated.
Cheers,
Joe
采纳的回答
Gareth Thomas
2011-8-29
Hi Joe,
Maybe I miss understood what you were aiming for but try logical indexing.
img = imread('pout.tif');
h_im = imshow(img);
e = imellipse(gca,[55 10 120 120]);
BW = createMask(e,h_im);
imshow(BW)
std2(img)
std2(img(BW))
Does this give you what you were looking for?
The idea here is simple. std2(A) gives the same as as std(A(:))
But the important thing is if you only want part of A, use the logical indexing to get those numbers.
Simple example:
a = [1 2 3 4; 2 3 4 5; 2 3 4 4; 4 4 1 2]
BW=a>=3
a(BW)
std2(a(BW))
Hope this helps.
更多回答（1 个）
David Young
2011-8-29
std(Image(logical(binary_mask)))
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