entropy.m

用matlab实现的JPEG算法

function [h,pdf]=entropy(v)

vv=v(:);
n=length(vv);
mx=round(max(vv));
mn=round(min(vv));
N=(mx-mn)+1;
pdf=zeros(1,N);
% make pdf ...
for i=1:n,
	ii=round(vv(i))-mn+1;
	pdf(ii)=pdf(ii)+1;
end
pdf=pdf/n;

%calc entropy...
h=etropy(pdf);