clear?all
close?all
load?head.mat;
%?head?=phantom（256）;
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%獲得扇形束等距離投影數(shù)據(jù)
D?=?512;????????????????????????????????????????????????????????????????????????????????%%%%射線源到圖象中心的距離
[shade]?=?fanbeam（headD‘FanSensorGeometry‘‘line‘‘FanSensorSpacing‘1）;????%%%%獲得投影數(shù)據(jù)?線形檢測(cè)器?通道數(shù)sp??旋轉(zhuǎn)角度360。
figure;
imshow（shade[]）;title（‘360度投影數(shù)據(jù)‘）;
clear?Xangle;
%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%修正投影數(shù)據(jù)
[XsizeYsize]?=?size（shade）;
for?n?=?1:Ysize
????for?m?=?1:Xsize
????????shade_temp（mn）?=?shade（mn）*D/sqrt（D.^2+（m-185）.^2）;
%?shade_temp（mn）?=?shade（mn）;
????end
end;
%?shade_temp?=?（D/sqrt（D.^2+（m-185）.^2））*shade;
clear?Xsize;
clear?Ysize;
figure
imshow（shade_temp[]）;
title（‘修正后的投影數(shù)據(jù)‘）;
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%進(jìn)行R_L卷積濾波

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%生成R_L卷積核
t=linspace（-128127256）;
filt=0.0085*（sinc（t）/2-sinc（t/2）.^2/4）;
figure;
plot（filt）;
title（‘R__L?濾波函數(shù)?256點(diǎn)‘）
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
tic
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%卷積濾波
shade?=?shade_temp;
clear?shade_temp;
shade_temp?=?zeros（881360）;
shade_temp（257:625:）?=?shade;
for?n?=?1:360
????temp（:n）?=?conv（shade_temp（:n）filt）;
end
clear?shade_temp;
%?%?%?%?%?%?%?%?%?%?shade_temp?=abs（temp（385:753:））;
shade_temp?=temp（385:753:）;
size（shade_temp）;
figure
imshow（shade_temp[]）;
title（‘濾波后投影數(shù)據(jù)‘）;
clear?filt;
clear?shade;
clear?temp;
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%進(jìn)行反投影
re?=?zeros（256256）;
d_th?=?pi/180;
for?view?=?1:360
????for?x?=?1:256
????????for?y?=?1:256
????????????u?=?（D-（x-128.5）*cos（（view-1）*d_th）-（y-128.5）*sin（（view-1）*d_th））;
????????????n?=?D*（-（x-128.5）*sin（（view-1）*d_th）+（y-128.5）*cos（（view-1）*d_th））/u+185;
????????????if?（1????????????????nn?=?fix（n）;?n0?=?n-nn;
%?????????????????re（xy）?=?（（1-n0）*shade_temp（nnview）+n0*shade_temp（nn+1view））*D^2/u^2;
????????????????re（xy）?=?re（xy）?+?（（1-n0）*shade_temp（nnview）+n0*shade_temp（nn+1view））*D^2/u^2;

????????????else?re（xy）?=?re（xy）;
????????????end
????????end
????end
%?????view
%?????figure
%?????imshow（re[]）
end
figure
imshow（re[]）
title（‘重建后的圖象‘）;
toc

figure?
imshow（head[]）
title（‘原始圖象‘）;
p1?=?re（128:）;
p2?=?head（128:）;
figure
plot（p1

?屬性????????????大小?????日期????時(shí)間???名稱
-----------?---------??----------?-----??----

?????文件???????3360??2009-06-07?20:58??fb_t.m

-----------?---------??----------?-----??----

?????????????????3360????????????????????1