SUSAN角点检测

close all;
clear all;
I=imread('corner2.gif');
[posX,posY]=susan(I,);
figure;
imshow(I);hold on;
plot(posX,posY,'g*');

function [posX,posY]=susan(I,radius)
%SUSAN角点检测
%I:输入图像
%radius:圆形模板的半径
%(posX,posY):角点坐标
[r,c]=size(I);
mask=generatemask(radius);
th1=;%阈值越小，提取的角点越多
th2=sum(mask(:))/;%阈值越大，提取的角点越多
R=zeros(r,c);%角点响应值
res=zeros(r,c);%是否是角点
for i=radius+:r-radius
    for j=radius+:c-radius
        B=I(i-radius:i+radius,j-radius:j+radius);
        usan=(abs(B-I(i,j))<th1).*mask;%USAN区域
        N=sum(usan(:));
        if(N<th2)
            R(i,j)=th2-N;
        end
    end
end

%非极大值抑制
tr=radius+;
for i=tr+:r-tr
    for j=tr+:c-tr
        tmp=R(i-tr:i+tr,j-tr:j+tr);
        tmp(tr+,tr+)=;
        if(R(i,j)>max(tmp(:)))
            res(i,j)=;
        end
    end
end
[posY,posX]=find(res);

function mask=generatemask(radius)
%生成半径为radius的掩模
mask=zeros(*radius+,*radius+);
[row,col]=size(mask);
cenr=(row+)/;
cenc=(col+)/;
for i=:row
    for j=:col
        if((i-cenr)^+(j-cenc)^<=radius^)
            mask(i,j)=;
        end
    end
end

结果：