matlab_傅立叶变换，等距离采样，等角度采样，轮廓提取，形态处理

function [output]=ff_transform(str); %str为图像文件名-------------------- data=side(str); [x,y]=size(data); index=1; for i=1:x for j=1:y if data(i,j)==1 s(index,1)=i; s(index,2)=j; index=index+1; end end end %--------------------------------------获取质心 x0=0; y0=0; for i=1:index-1 x0=x0+s(i,1); y0=y0+s(i,2); end x0=x0/(index-1); y0=y0/(index-1); %---------------------------------------获取顺序轮廓数据 outline_data=out_line(data,s); %----------------------------------------重构图像 recon(outline_data); %output=outline_data; %---------------------------------------判断是等角度还是等距离采样 dis_angle=input('Do you want use equal dis? Y/N [Y]: ', 's'); if dis_angle=='Y'; after_data=equal_dis(outline_data); end if dis_angle=='N' after_data=equal_angle(outline_data,x0,y0); end %r(i)为轮廓像素点到质心的距离 for i=1:max(size(after_data)) r(i)=sqrt((after_data(i,1)-x0).^2+(after_data(i,2)-y0).^2); end %fft:表示傅立叶变换,FFT表示变换后的结果 output=fft(r); %function side------------------ function outside=side(str); origin_image=imread(str); level=graythresh(origin_image); gray_image=im2bw(origin_image,level); se=strel([0 1 0;1 1 1;0 1 0]); erode_image=imerode(gray_image,se); %imshow(erode_image); final_image=imsubtract(gray_image,erode_image); outside=final_image; figure: imshow(final_image); %final_image:为轮廓矩阵 %function out_line(data,s)----------------获取轮廓数据，顺序方式的,只适合轮廓边界是连续的情况. function [order_data]=out_line(data,s) [xmax,ymax]=size(data) order_data(1,1)=s(1,1); order_data(1,2)=s(1,2); xx=order_data(1,1); yy=order_data(1,2); i=2; s1=0; condition=1; j=0; while condition~=0 s1=i; if (xx-1)&&data(xx-1,yy)==1&&~is_vector([xx-1 yy],order_data) order_data(i,1)=xx-1; order_data(i,2)=yy; xx=order_data(i,1); yy=order_data(i,2); i=i+1; end if (xx-1)&&(yy-1)&&data(xx-1,yy-1)==1&&~is_vector([xx-1 yy-1],order_data) order_data(i,1)=xx-1; order_data(i,2)=yy-1; xx=order_data(i,1); yy=order_data(i,2); i=i+1; end if (yy-1)&&data(xx,yy-1)==1&&~is_vector([xx yy-1],order_data) order_data(i,1)=xx; order_data(i,2)=yy-1; xx=order_data(i,1); yy=order_data(i,2); i=i+1; end if ((xx+1)<=xmax)&&(yy-1)&&data(xx+1,yy-1)==1&&~is_vector([xx+1 yy-1],order_data) order_data(i,1)=xx+1; order_data(i,2)=yy-1; xx=order_data(i,1); yy=order_data(i,2); i=i+1; end if ((xx+1)<=xmax)&&data(xx+1,yy)==1&&~is_vector([xx+1 yy],order_data) order_data(i,1)=xx+1; order_data(i,2)=yy; xx=order_data(i,1); yy=order_data(i,2); i=i+1; end if ((xx+1)<=xmax)&&((yy+1)<=ymax)&&data(xx+1,yy+1)==1&&~is_vector([xx+1 yy+1],order_data) order_data(i,1)=xx+1; order_data(i,2)=yy+1; xx=order_data(i,1); yy=order_data(i,2); i=i+1; end if ((yy+1)<=ymax)&&data(xx,yy+1)==1&&~is_vector([xx yy+1],order_data) order_data(i,1)=xx; order_data(i,2)=yy+1; xx=order_data(i,1); yy=order_data(i,2); i=i+1; end if (xx-1)&&((yy+1)<=ymax)&&data(xx-1,yy+1)==1&&~is_vector([xx-1 yy+1],order_data) order_data(i,1)=xx-1; order_data(i,2)=yy+1; xx=order_data(i,1); yy=order_data(i,2); i=i+1; end if s1==i xx=order_data(i-2,1); yy=order_data(i-2,2); if j==i condition=0; end j=i; end end %function after_data=equal_dis(out_data)----------------按等曲线距离采样 function after_data=equal_dis(out_data) dis=input('please input the interval of image outline data:'); after_data(1,1)=out_data(1,1); after_data(1,2)=out_data(1,2); length=max(size(out_data)); len=0; j=1; for i=1:length-1 if len<dis len=len+sqrt((out_data(i,1)-out_data(i+1)).^2+(out_data(i,2)-out_data(i+1,2)).^2); else len=0; j=j+1; after_data(j,1)=out_data(i+1,1); after_data(j,2)=out_data(i+1,2); end end %function %after_data=equal_angle(out_data,x0,y0)---------------------------等角度采样,在实际 %中不太可能严格相等，所以设置一个阈值，阈值选取的合理性决定了最后采样的数据点数 function after_data=equal_angle(out_data,x0,y0) N=input('please input the number of share angle'); if N>max(size(out_data)) error('N must be smaller than the size of out_data'); end angle=pi/N; K=1; for j=1:max(size(out_data)) i=0; while i<N if abs(tan(angle*i)-(out_data(j,1)-x0)/(out_data(j,2)-y0))<0.015; after_data(K,1)=out_data(j,1); after_data(K,2)=out_data(j,2); K=K+1; break; end i=i+1; end end %function is_vector---------------判断一向量是否为另一向量的子向量,child为1*2,mother为n*2 function mark=is_vector(child,mother) [x,y]=size(mother); mark=1; for i=1:x mark=1; for j=1:y mark=(mother(i,j)==child(1,j))*mark; end if mark break; end end if (i==x)&&(j==y)&&~mark mark=0; end %function recon(data)-------------重构图像 function recon(data) [x,y]=max(data); image_data=zeros(x,y); [x1,y1]=size(data); for i=1:x1 xaxe=data(i,1); yaxe=data(i,2); image_data(xaxe,yaxe)=1; end figure:imshow(image_data);