djxx.m

来自「车道检测中弯道的检测」· M 代码 · 共 41 行

function T=djxx(X)
%大津法根据背景和前景的类间方差值来求解图像的最优域值
%大津法根据的原理是利用类别方差作为判据，选取使类间方差最大和类内方差最小的图像灰度值作为最佳域值
[m,n]=size(X);
N=m*n;
num=zeros(1,256);
p=zeros(1,256);

for i=1:m
    for j=1:n
       num(X(i,j)+1)=num(X(i,j)+1)+1;%num[n]表示灰度值为n的像素点的个数
    end
end

for i=0:255;
    p(i+1)=num(i+1)/N;%p[n]表示灰度值的密度
end
totalmean=0;
for i=0:255;
    totalmean=totalmean+i*p(i+1);
end
maxvar=0;

for k=0:255
   kk=k+1;
   zerosth=sum(p(1:kk));
   firsth=0;
   for h=0:k
      firsth=firsth+h*p(h+1);
   end
   var=totalmean*zerosth-firsth;
   var=var*var;
   var=var/(zerosth*(1-zerosth)+0.01);
   var=sqrt(var);
   if(var>maxvar)
      maxvar=var;
      point=k;
   end
end

T=point;