www.pudn.com > 666bandelets_toolbox.zip > evaluate_nbr_bits.m

function m = evaluate_nbr_bits(M,T) 
 
% evaluate_nbr_bits - evaluate the number of bits to code an image 
% 
%   m = evaluate_nbr_bits(M) 
% 
%   nbr_bit is a lower bound (Shanon entropy bound) on the number  
%       of bits needed to code the wavelet image. 
% 
%   Works also with cell array of matrix. 
% 
%   Copyright (c) 2004 Gabriel Peyré 
 
if iscell(M) 
    m = 0; 
    for i=1:length(M) 
        m = m + evaluate_nbr_bits(M{i},T); 
    end 
    return; 
end 
     
[y, nbr_bits, nbr_bits_tot, M] = perform_quantization(M, T); 
 
M = M(:); 
n = length(M); 
h = []; % histogram 
for p = unique(M)'; 
    h = [h, length(find(M==p))]; 
end 
h = h/n; 
m = - n * sum( h.*log2(h) );