How is the effectiveness metric in Otsu's method (graythresh) calculated?

What is the mathematical formula used to evaluate threshold effectiveness metric in graythresh method? What is the best way to use this metric?

Answer 1

[Image Analyst]

I don't know and I wouldn't worry about it. It either works or it doesn't, and in my experience, it usually doesn't. It only seems to work well with images that have a uniform background and a nicely bimodal histogram, which is rarely encountered in the real world except in things like machine vision apps that are looking at parts, like for a robot "pick and place" type of app.