f=imread('Fig3.15(a)4.jpg');
[m,n]=size(f);
g=zeros(m,n);
%f1=double(f);
c=255;
result=0;
y=zeros(1,256);
z=zeros(1,256);
x=zeros(1,256);
%计算原图所有灰度级像素数y(k)
for i=1:m
for j=1:n
t=f(i,j);
y(t+1)=y(t+1)+1;
end
end
%原图灰度分布概率z(k)
for k=1:256
z(k)=y(k)/(m*n);
end
%计算统计概率x(k)
for k1=1:256
result=result+z(k1);
x(k1)=result;
end
%统计概率取整
x=round(c*x);
for i1=1:m
for j1=1:n
g(i1,j1)=x(f(i1,j1)+1);
end
end
G=uint8(g);
figure(2);imshow(G);title('均衡化');
figure(3);histeq(f);