基于MATLAB的圖像分割技術
利用閥值法對圖像進行分割：
>> f=imread('peppers.png');
>> f=rgb2gray(f);
>> f=im2double(f);
>> t=0.5*(min(f(:))+max(f(:)));
>> done=false;
>> while ~done
g=f>=t;
tn=0.5*(mean(f(g))+mean(f(~g)));
done=abs(t-tn)<0.1;
t=tn;
end;
>> display('Threshold(t)-Iterative');
Threshold(t)-Iterative
>> t
t =
0.4691
>> r=im2bw(f,t);
>> subplot(2,2,1);imshow(f);
>> subplot(2,2,2);imshow(r);
>> xlabel('疊代法全局閥值分割');
>> th=graythresh(f);
>> th
th =
0.3961
>> s=im2bw(f,th);
>> subplot(2,2,3);imshow(s);
>> xlabel('全局閥值Otsu分割');
>> se=strel('disk',10);
>> ft=imtophat(f,se);
>> thr=graythresh(ft);
>> thr
thr =
0.1098
>> lt=im2bw(ft,thr);
>> subplot(2,2,4);imshow(lt);
>> xlabel('局部閥值分割');
用疊代法對圖像進行分割：
>> i=imread('eight.tif');
>> zmax=max(max(i));
>> zmin=min(min(i));
>> tk=(zmax+zmin)/2;
>> bcal=1;
>> isize=size(i);
>> while (bcal)
ifg=0;
ibg=0;
fg=0;
bg=0;
for j=1:isize(1)
for k=1:isize(2)
tmp=i(j,k);
if(tmp>=tk)
ifg=ifg+1;
fg=fg+double(tmp);
else
ibg=ibg+1;
bg=bg+double(tmp);
end;
end;
end;
zo=fg/ifg;
zb=bg/ibg;
tktmp=uint8((zo+zb)/2);
if(tktmp==tk)
bcal=0;
else
tk=tktmp;
end;
end;
>> disp(strcat('疊代後閥值',num2str(tk)));
疊代後閥值165
>> newi=im2bw(i,double(tk)/255);
>> subplot(1,2,1);imshow(i);
>> subplot(1,2,2);imshow(newi);
>> xlabel('疊代法');
用Otsu法進行閥值選擇：
>> i=imread('coins.png');
>> subplot(1,2,1);imshow(i);
>> bw=im2bw(i,graythresh(getimage));
>> subplot(1,2,2);imshow(bw);
使用分水嶺算法對圖像進行分割：
>> c1=-10;
>> c2=-c1;
>> dist=sqrt(2*(2*c1)^2);
>> rad=dist/2*1.4;
>> li=[floor(c1-1.2*rad) ceil(c2+1.2*rad)];
>> [x,y]=meshgrid(li(1):li(2));
>> bw1=sqrt((x-c1).^2+(y-c1).^2)<=rad;
>> bw2=sqrt((x-c2).^2+(y-c2).^2)<=rad;
>> bw=bw1|bw2;
>> subplot(1,3,1);imshow(bw);
>> d=bwdist(~bw);
>> subplot(1,3,2);imshow(d,[]);
>> d=-d;
>> d(~bw)=-In