第十单元 第4课 实验 2017年全国大学生 数学建模竞赛A题

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1 第十单元 第4课 实验 2017年全国大学生 数学建模竞赛A题

2 问题三的代码： function[attach5_reconstruct256,attach4_absorb10]=problem3(input_args) %1.对有偏移的CT投影进行校准 alpha=atan(-x0/y0)*180/pi; reconstruct_radon=zeros(size(attach5_radon)); figure; for i=1:180     theta=(i-1)*delta_angle;     attach5_radon_anglei=find(abs(direction180-theta)<delta_angle/2);     if isempty(attach5_radon_anglei)          attach5_radon_anglei=find(abs(direction theta)<delta_angle/2);     end     if theta<start_angle-delta_angle        reconstruct_radon(:,i)=flipud(attach5_radon(:,attach5_radon_anglei));     else        reconstruct_radon(:,i)=attach5_radon(:,attach5_radon_anglei);

3  end     if abs(theta)<delta_angle         d=abs(x0);     elseif  abs(theta-180)<delta_angle%k=0,水平方向投影          d=y0;     else         k=tan(theta*pi/180+pi/2);         d=abs(-k*x0+y0)/sqrt(1+k^2);     end     address_num=round(d/sepdist);     if address_num>0           if theta<=alpha |  theta>180+alpha           reconstruct_radon(:,i)=[reconstruct_radon(address_num+1:end,i);zeros(address_num,1)];           else     reconstruct_radon(:,i)=[zeros(address_num,1);reconstruct_radon(1:end-address_num,i)];           end

4 plot([1:N],reconstruct_radon(:,i));
    hold on; end  grid on;  xlabel('投影地址');  ylabel('投影值');  title(sprintf('重新校准之后的附件5的各方向投影'));  saveas(gcf,sprintf('重新校准之后的附件5的各方向投影'),'jpg');  %2.根据投影校准之后的reconstruct_radon利用iradon反变换重构附件5的原图像  attach5_reconstruct362=iradon(reconstruct_radon,theta180);  imwrite(attach5_reconstruct362,'重构附件5的362X362图像.jpg','jpg');  attach5_reconstruct256=imresize(attach5_reconstruct362,[ ]);

5  [row,col]=find(attach5_reconstruct256<0);
 for i=1:length(row)      attach5_reconstruct256(row(i),col(i))=0;  end  figure;imshow(attach5_reconstruct256,[]);title('重构附件5的256X256图像');  imwrite(attach5_reconstruct256,'重构附件5的256X256图像.jpg','jpg');  xlswrite('problem3.xls',attach5_reconstruct256);  %3.重构附件5的吸收率图像中由附件4中指定的10个位置处的吸收率   r=1;  attach4_10pos_pixel=round(attach4_10pos*256/100);   t=attach4_10pos_pixel(:,2);   attach4_10pos_pixel(:,2)=attach4_10pos_pixel(:,1);   attach4_10pos_pixel(:,1)=256-t;   for i=1:size(attach4_10pos_pixel,1)       attach4_absorb10(i,1)=gain*mean(mean(attach5_reconstruct256...

6 (attach4_10pos_pixel(i,1)-r:attach4_10pos_pixel(i,1)+r,attach4_10pos_pixel(i,2)-r:attach4_10pos_pixel(i,2)+r)));   end   attach4_absorb10=abs(attach4_absorb10);   xlswrite('附件4指定的10个位置处的吸收率.xls',attach4_absorb10);