How to use k-means clustering using only b* channel in L*a*b* model?

I want to cluster background,disease portion and non-disease portion in an image but its not working for my image.It shows the error..

Answer 1

[Image Analyst]

You forgot to post your error message. In the meantime, see this example: http://www.mathworks.com/products/demos/image/color_seg_k/ipexhistology.html

[Sabanam]

Above link not working for single channel

[Image Analyst]

What are your two axes in your scatterplot?