radial_sum.asv

图像重建中投影建模算法对二维图像进行投影值计算的程序

function s=radial_sum(photo_matrix,r,theta)
    weishu=size(photo_matrix);
    N=weishu(1);
        if 0<=theta&theta<=45 
            theta0=theta;flag=1;
        elseif 45<=theta&theta<=90
            theta0=90-theta;flag=2;
        elseif 90<=theta&theta<=135
            theta0=theta-90;flag=3;
        elseif  135<=theta&theta<=180
            theta0=180-theta;flag=4;
        else  
            flag=0;
        end;
        cover=radial_cover(N,-r,theta0);
        switch flag
            case 0 
                error('the theta is out of range!');
            case 1
               cover_matrix=radial_cover(N,r,theta0);
            case 2
               cover_matrix=cover';
            case 3
                cover=radial_cover(N,r,theta0);
                cover_matrix=flipud(cover');
            case 4
                cover=radial_cover(N,r,theta0);
                cover_matrix=fliplr(cover);
         end;
   
   covered=photo_matrix.*cover_matrix;
   X_sum=sum(covered,1);
   s=sum(X_sum);