求图像互信息Matlab代码

function mi = MI(a,b) %Caculate MI of a and b in the region of the overlap part %计算重叠部分 [Ma,Na] = size(a); [Mb,Nb] = size(b); M=min(Ma,Mb); N=min(Na,Nb); %初始化直方图数组 hab = zeros(256,256); ha = zeros(1,256); hb = zeros(1,256); %归一化 if max(max(a))~=min(min(a))     a = (a-min(min(a)))/(max(max(a))-min(min(a))); else     a = zeros(M,N); end if max(max(b))-min(min(b))     b = (b-min(min(b)))/(max(max(b))-min(min(b))); else     b = zeros(M,N); end a = double(int16(a*255))+1; b = double(int16(b*255))+1; %统计直方图 for i=1:M     for j=1:N        indexx =  a(i,j);        indexy = b(i,j) ;        hab(indexx,indexy) = hab(indexx,indexy)+1;%联合直方图        ha(indexx) = ha(indexx)+1;%a图直方图        hb(indexy) = hb(indexy)+1;%b图直方图    end end %计算联合信息熵 hsum = sum(sum(hab)); index = find(hab~=0); p = hab/hsum; Hab = sum(sum(-p(index).*log(p(index)))); %计算a图信息熵 hsum = sum(sum(ha)); index = find(ha~=0); p = ha/hsum; Ha = sum(sum(-p(index).*log(p(index)))); %计算b图信息熵 hsum = sum(sum(hb)); index = find(hb~=0); p = hb/hsum; Hb = sum(sum(-p(index).*log(p(index)))); %计算a和b的互信息 mi = Ha+Hb-Hab; %计算a和b的归一化互信息 %mi = Hab/(Ha+Hb);