function?level?=?MinimumCrossEntropyThreshold（I）
%?Nikhil?R.?Pal?On?Minimum?Cross-Entorpy?Thresholding?
%?Pattern?Recognition?29（4）?1996?575-580?
%
%
%???Example
%???-------
%???????I?=?imread（‘coins.png‘）;
%???????level?=?MinimumCrossEntropyThreshold（I）;
%?
%?Update:?2009.2.28?23:42:00
%?Author:?WangJun?wangjun_sytu@sina.com
I1=imread（‘11.jpg‘）;
I=rgb2gray（I1）;
L?=?256;
gray?=?0:1:L-1;
h?=?hist（reshape（I?1?size（I1）*size（I2））?gray）;
p?=?h/sum（h）;
%?warning?off?MATLAB:divideByZero
%?
%?s_lower?=?2;
%?s?=?2;
%?while?sum（h（1:s））?==?0
%?????s_lower?=?s_lower?+?1;
%?????s?=?s+1;
%?end
%?s_upper?=?L-1;
%?s?=?L-1;
%?while?sum（h（s+1:L））?==?0
%?????s_upper?=?s_upper?-?1;
%?????s?=?s-1;
%?end

for?s?=?2:?L-1?????????%?s:?閾值
????%?Compute?p_o?and?p_b?using?equation?（5）?and?（6）
????sum_ho?=?sum（h（1:s））;
????sum_hb?=?sum（h（s+1:L））;
????po?=?zeros（1s）;
????if?sum_ho?~=0
????????po?=?h（1:s）/sum_ho;
????end
????pb（s+1:L）?=?zeros（1?L-s）;
????if?sum_hb?~=?0
????????pb（s+1:L）?=?h（s+1:L）/sum_hb;
????end
????
????%?Compute?landa_o?and?landa_b?using?equation?（10）?and?（11）
????landa_o?=?0;
????if?sum_ho?~=?0
???????