how to segment white matter, gray matter ,csf in an gray image using otsu thresholding method?

i need to partition segment white matter, gray matter ,csf to find the tumors in an image

Answer 1

[Image Analyst]

The otsu method is rarely very good except in high contrast images with a bimodal histogram. I doubt it would do a satisfactory job on any anatomical or biological images. It will probably get the whole skull and the background, not all those types of tissue you referred to. Nonetheless, to use Otsu you use the functions graythresh() and im2bw(). When you discover that doesn't work, then you can look at successful methods that have been published: in VisionBib