www.pudn.com > MatlabSIFTcode_1.rar > construct_key.m

 
function key = construct_key(px, py, img, sz) 
 
    pct = .75; 
     
    [h,w] = size(img); 
     
    [yoff,xoff] = meshgrid(-1:1,-1:1); 
    yoff = yoff(:)*pct; 
    xoff = xoff(:)*pct; 
     
    for i = 1:size(yoff,1) 
        ctrx = px + xoff(i)*sz*2;  %method using interpolated values 
        ctry = py + yoff(i)*sz*2; 
        [y,x] = meshgrid(ctry-sz:sz/3:ctry+sz,ctrx-sz:sz/3:ctrx+sz); 
        y=y(:); 
        x=x(:); 
        t = 0; 
        c = 0; 
        for k=1:size(y,1) 
            if x(k)1 & y(k)1  
                t = t + interp(img,x(k),y(k)); 
                c=c+1; 
            end 
        end 
        if c==0 
            c 
        end 
        t = t/c; 
         
        key(i) = t; 
    end 
    
    key = key/sum(key);