What's the difference between GrayThresh and OtsuThresh?

Its seems that both of them find the optimum threshold with Otsu algorithm. So what's the difference between them? Thank you.

Answer 1

[Guillaume]

The only significant difference is that graythresh wants the image as input, whereas otsuthresh wants the image histogram instead. You can look at the actual code of both

edit graythresh
edit otsuthresh

and you'll see that all graythresh does is to compute the image histogram with 256 bins before calling otsuthresh.

[nadav potasman]

Thank you very much!