Question

求一个用otsu算法的图像分割matlab程序

Answer 1

image_1=imread('E:\ebook\lena.bmp'); %读入图片
image_1=rgb2gray(image_1);%灰度化

[m,n]=size(image_1);%计算图片的像素点个数,行列,n是列数，Gray

num=zeros(1,256);%存放各灰度级出现的次数

p=zeros(1,256);%存放各灰度级的比率

image_1=double(image_1);%双精度化

for i=1:m
for j=1:n
num(image_1(i,j)+1)=num(image_1(i,j)+1)+1;%统计各灰度级的像素点个数
end
end

for i=1:256
p(i)=num(i)/(m*n);%计算各灰度级出现的比率
end

for i=2:256
if p(i)~=0
st=i+1;%实现寻找出现比率不为0的最小灰度值
break
end
end

for i=256:-1:1
if p(i)~=0;
nd=i-1;%实现找出出现比率不为0的最大灰度值
break
end
end

%以下程序实现利用最小方差和法找出门阈值
w=inf; th=0;

for t=st:nd%最小非零比率灰度值到最大非零比率灰度值
qt1=0; qt2=0;%前景后景像素点比率
u1=0; u2=0;%前景后景均值
v1=0; v2=0;%
for i=1:t
qt1=qt1+p(i);
end
for i=1:t
u1=u1+i*p(i)/qt1;
end
for i=1:t
v1=v1+((i-u1)^2)*p(i)/qt1;
end

for i=t+1:256
qt2=qt2+p(i);
end
for i=t+1:256
u2=u2+i*p(i)/qt2;
end
for i=t+1:256
v2=v2+((i-u2)^2)*p(i)/qt2;
end
if qt1*v1+qt2*v2<w
th=t; w=qt1*v1+qt2*v2 ;
end
end

for i=1:m
for j=1:n
if (image_1(i,j)+1>th)
image_2(i,j)=255;
else
image_2(i,j)=0;
end
end
end
image_2=uint8(image_2);%读入读出变换
figure,imshow(image_2);%显示二值化后的图片