How to correct the assignment Error?

I have to run the K-means clustering program using matlab.

im = imread('D:\lena256.jpg');
k=5; 
%histogram calculation
img_hist = zeros(256,1);
hist_value = zeros(256,1);
for i=1:256
  img_hist(i)=sum(sum(im==(i-1)));    
end

Run above code the following error occurred.

??? In an assignment  A(:) = B, the number of elements in A and B
must be the same.
Error in ==> kmeansclustering at 10
  img_hist(i)=sum(sum(im==(i-1)));
Error in ==> main at 5
[clusters, result_image, clusterized_image] = kmeansclustering(im,k);

How do I solve this problem?

[José-Luis]

Please edit your post. It makes it easier for people to understand your question, and shows a modicum of interest on your part.

Your problem is that

 img_hist(i)

and

 sum(sum(im==(i-1)))

are of different sizes.

[Matt J]

Incidentally, why not use HISTC to generate the histogram? Why re-invent that wheel with for-loops?

[PRIYANGA]

ok Sir I have to try.

Answer 1

[José-Luis]

Try

 img_hist(i)= sum(sum(sum(im==(i-1))));

im might be a three dimensional matrix.

[PRIYANGA]

Thank You So Much Sir. Its working

[José-Luis]

My pleasure, but please edit your posts for clarity in the future.

Answer 2

[Jürgen]

Hi,

there is a function: imhist(I) , quite useful for this work, + if you want to calculate the hist by summing for each value 0=>255 you will get a array with a lenght of 256 not 256*256

regards,J

[Jürgen]

and indeed the comment of JL above is also a good point: the image could be a (VertRes, HorRes,3) matrix