img robert交叉梯度

>> i=imread('4.jpg');
>> imshow(i);
>> i=double(i);
>> w1=[-1 0;0 1];
>> w2=[0 -1;1 0];
>> g1=imfilter(i,w1,'corr','replicate');
>> g2=imfilter(i,w2,'corr','replicate');
>> g=abs(g1)+abs(g2);
>> figure,imshow(g,[]);
>> figure,imshow(abs(g1),[]);
>> figure,imshow(abs(g2),[]);
>>