how can i calculate variance of the intensity in an gray scale image

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kalaivaani
kalaivaani 2013-8-7
评论： chitresh 2013-11-30
in order to find the sigmoid function value of the image , i need the value of *mean and variance of the intensity of the image *

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回答（2 个）

chitresh
chitresh 2013-11-30
a = imread('input.tif'); % convet uint8 to double a_double = double(a); % get number of rows and columns value [r,c] = size(a); % mean of gray scale image total_mean = sum(a_double(:))/(r*c); % variance of gray scale image total_difference = (a_double - total_mean).^2; total_sum = sum(total_difference(:)); limit = (r*c)-1; total_variance = total_sum/limit;
please accept answer if its ok with you
Image Analyst
Image Analyst 2013-11-30
meanGrayLevel = mean2(grayImage); % or mean(grayImage(:));
variance = var(grayImage(:));
  1 个评论
chitresh
chitresh 2013-11-30
if you trying above code then try this else u find some error
grayimage_double = double(grayimage);
variance = var(grayimage_double);

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