how to calculate otsu threshold value for the matrix given [1 3 4 5 3 2; 4 6 2 4 1 9; 0 4 9 5 8 3; 2 4 9 4 2 1; 0 1 9 3 4 8; 5 6 4 7 3 8]

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Sanaullah Shareef Mohammed 2022-9-22

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https://ww2.mathworks.cn/matlabcentral/answers/1810285-how-to-calculate-otsu-threshold-value-for-the-matrix-given-1-3-4-5-3-2-4-6-2-4-1-9-0-4-9-5-8-3

评论： Image Analyst 2022-9-22

please help me with the simples code possible.

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Answer 1

Image Analyst 2022-9-22

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在 MATLAB Online 中打开

grayImage = uint8([1 3 4 5 3 2; 4 6 2 4 1 9; 0 4 9 5 8 3; 2 4 9 4 2 1; 0 1 9 3 4 8; 5 6 4 7 3 8])
grayImage = 6×6
   1   3   4   5   3   2
   4   6   2   4   1   9
   0   4   9   5   8   3
   2   4   9   4   2   1
   0   1   9   3   4   8
   5   6   4   7   3   8
threshold = graythresh(grayImage) % Find threshold using Otsu method.
threshold = 0.0196
% If it's uint 8 you want to multiply by 255
threshold = 255 * graythresh(grayImage)
threshold = 5

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Sanaullah Shareef Mohammed 2022-9-22

what if we want to calculate weights, means and varience for each element using loop and printing the minimum of all.

Image Analyst 2022-9-22

在 MATLAB Online 中打开

Not sure what that means. An element of the image is a single number and the mean is the value of the pixel, the variance is zero, and the max and min are again the value of the pixel.

If you want it of just the part above the threshold you'd do

grayImage = uint8([1 3 4 5 3 2; 4 6 2 4 1 9; 0 4 9 5 8 3; 2 4 9 4 2 1; 0 1 9 3 4 8; 5 6 4 7 3 8]);
threshold = graythresh(grayImage); % Find threshold using Otsu method.
% If it's uint 8 you want to multiply by 255
threshold = 255 * graythresh(grayImage)
threshold = 5
mask = grayImage > threshold;
meanGrayLevel = mean(grayImage(mask))
meanGrayLevel = 7.9000
varGrayLevel = var(double(grayImage(mask)))
varGrayLevel = 1.4333
stDevGrayLevel = std(double(grayImage(mask)))
stDevGrayLevel = 1.1972
minGrayLevel = min(grayImage(mask))
minGrayLevel = uint8
    6
maxGrayLevel = max(grayImage(mask))
maxGrayLevel = uint8
    9