clc;
load clown
image(X);
colormap(map);
data = reshape(X,320*200,1);
n = imhist(X,map);
n = n./64000;
(-1)*sum(n.*log2(n))
symbols = [1:81];
[dict,avglen] = huffmandict(symbols,n)
comp = huffmanenco(data,dict);
dsig = huffmandeco(comp,dict);