error in kmeans

I have 10 images i tried using 

[IDX,C] = kmeans(I,10)

but i get error

Class of operand is not supported.

please help

for x = 1:length(dirlist)

I = (imread([pathname, dirlist(x).name]));
I=rgb2gray(I);
I =imresize(I ,[512 512]);
size(I);
[IDX,C] = kmeans(I,10)

Answer 1

[Wayne King]

What version of MATLAB are you using? Are you sure you are using a MathWorks' version of kmeans.m? If you enter:

>>which kmeans

what do you get returned? Is it something like:

toolbox\stats\stats\kmeans.m

At any rate, try:

[IDX,C] = kmeans(double(I),10);