Is there is any difference between otsu & graythresh??

i am trying to make image segmentation using otsu's method but i am confused about the difference between using that function (IDX = otsu()) or using graythresh(I) ,Regarding that the first function didn't work and always that error appears (??? Undefined function or method 'otsu' for input arguments of type'double'.)...

Answer 1

[Image Analyst]

You may find Otsu doesn't work well. It seems to work best for high contrast images with well separated bimodal histograms. If you have a skewed unimodal histogram, it often doesn't pick what you'd pick if you did it manually (with my thresholding app: http://www.mathworks.com/matlabcentral/fileexchange/29372-thresholding-an-image). Personally I like the triangle method better - it seems to work with more images that are continuous gray scale.

Answer 2

[Sean de Wolski]

graythresh is MATLAB's Image Processing Toolbox's implementation of the Otsu algorithm.

doc graythresh

Explains this in the references.

[Mariam Sheha]

Thank you for answering my question, but did you know if their is anther matlab equation named by "_otsu_" where i found matlab code using it but it dosn't work properly....

please if you have any further information about that issue report me...

Thanks A lot :)

[Sean de Wolski]

There are a few functions on the FEX with that name:

http://www.mathworks.com/matlabcentral/fileexchange/index?utf8=%E2%9C%93&term=otsu

But I would avoid them in favor of the IPT standard.

Answer 3

[Mariam Sheha]

Thanks A lot, your answer is helpful...