I've created my own Otsu thresholding function, but is isn't working properly

I'm trying to implement my own otsu thresholding algorithm.

The input of this function is an grayscale map of an image and the output is the thresholded image and the 'within class variance' to check the result.

I've been stuck on this for several days and can't find the problem with the algorithm. This function gives a very different result from the built-in otsu threshold function.

function [wcv,thresholdedImage] = otsuthreshold(im,varargin)
    if(nargin == 1)
        [hist,values] = imhist(im);
        histLength = length(hist);
        histTotal = sum(hist);

        wcv = zeros(1,histLength-1); %within class variance

        for i = 1:histLength-1
            %Weight
            wb = sum(hist(1:i))/histTotal;
            wf = sum(hist(i+1:end))/histTotal;
            %Mean
            ub = sum(hist(1:i).*values(1:i))/sum(hist(1:i));
            uf = sum(hist(i+1:end).*values(i+1:end))/sum(hist(i+1:end));
            %Variance
            vb = sum(power(hist(1:i)-ub,2).*values(1:i))/sum(hist(1:i));
            vf = sum(power(hist(i+1:end)-uf,2).*values(i+1:end))/sum(hist(i+1:end));

            wcv(i) = wb*vb^2+wf*vf^2;
        end

        [~,index] = min(wcv);
    else
        index = varargin{1};
        wcv = [];
    end
       
    im(im <= index) = 0;
    im(im > index) = 255;
    thresholdedImage = im;
end

[dpb]

See if

https://blogs.mathworks.com/steve/2016/06/14/image-binarization-otsus-method/

helps any...

Answer 1

[Image Analyst]

See how the Mathworks does it:

>> edit otsuthresh.m