f=imread('C:\Users\yuzheng\Desktop\ipt\IR20120412_0896.jpg');
>> g=rgb2gray(f);
>> h=fspecial('sobel');
>> fd=double(g);
>> t1=imfilter(fd,h,'replicate');
>> t2=imfilter(fd,h','replicate');
>> k=sqrt(t1.^2+t2.^2);
>> g2=imclose(imopen(k,ones(3,3)),ones(3,3));
>> im=imextendedmin(g,3);
>> im=imextendedmin(g,10);
>> Lim=watershed(bwdist(im));
>> em=Lim==0;
>> g2=imimposemin(k,im|em);
>> L2=watershed(g2);
>> f2=g;
>> f2(L2==0)=255;
>> imshow(f2)
