How to divide classes in optimum global thresholding using Otsu's method

I am implementing optimum global thresholding using otsu's method by referring Gonzalez and Woods book, I am finding difficulty in dividing classes and calculating of cumulative sums, please provide me an matlab code for this algorithm.

Answer 1

[Matt J]

See multithresh() or graythresh()

[Deepika Rani]

Thanku...I checked with graythresh, but for the same image I am computing, I need to change the threshold values how can I do means I need to check with different threshold values like t=6,t=64,t=128. Please help me with this with a matlab code

[Matt J]

You can do that with imquantize.