低通滤波的matlab实现.doc

四种低通滤波器： 一、理想低通滤波器 I=imread(bb.jpg); T=rgb2gray(I); figure(1); subplot(1,2,1),imshow(uint8(I)); title(原图像); subplot(1,2,2),imshow(uint8(T)); title(理想低通滤波所得图像); [f1,f2]=freqspace(size(T),meshgrid); H=ones(size(T)); r=sqrt(f1.^2+f2.^2); H(r0.1)=0; Y=fft2(double(T)); Y=fftshift(Y); Ya=Y.*H; Ya=ifftshift(Ya); I=ifft2(Ya); figure(2); surf(H,Facecolor,interp,Edgecolor,none,Facelighting,phong); title(频谱图); 二、巴特沃斯低通滤波器 I=imread(bb.jpg); T=rgb2gray(I); figure(1); subplot(1,2,1),imshow(uint8(I)); title(原图像); subplot(1,2,2),imshow(uint8(T)); title(巴特沃斯低通滤波所得图像); [f1,f2]=freqspace(size(T),meshgrid); D=0.3; r=f1.^2+f2.^2; n=4; for i=1:size(T,1) for j=1:size(T,2) t=r(i,j)/(D*D); H(i,j)=1/(t^n+1); end end Y=fft2(double(T)); Y=fftshift(Y); Ya=Y.*H; Ya=ifftshift(Ya); I=real(ifft2(Ya)); figure(2); surf(H,Facecolor,interp,Edgecolor,none,Facelighting,phong); title(频谱图); 三、梯形滤波器 I=imread(bb.jpg); T=rgb2gray(I); figure(1); subplot(1,2,1),imshow(uint8(I)); title(原图像); subplot(1,2,2),imshow(uint8(T)); title(梯形低通滤波所得图像); [f1,f2]=freqspace(size(T),meshgrid); D=100/size(I,1); D0=0.1; D1=0.4; r=sqrt(f1.^2+f2.^2); H=zeros(size(T)); H(rD0)=1; for i=1:size(T,1) for j=1:size(I,2) if r(i,j)=D0 r(i,j)=D1 H(i,j)=(D1-r(i,j))/(D1-D0); end end end Y=fft2(double(T)); Y=fftshift(Y); Ya=Y.*H; Ya=ifftshift(Ya); I=real(ifft2(Ya)); figure(2); surf(H,Facecolor,interp,Edgecolor,none,Facelighting,phong); title(频谱图); 四、高斯低通滤波器 I=imread(bb.jpg); T=rgb2gray(I); figure(1); subplot(1,2,1),imshow(uint8(I)); title(原图像); subplot(1,2,2),imshow(uint8(T)); title(高斯低通滤波所得图像); [f1,f2]=freqspace(size(T),meshgrid); D=100/size(I,1); r=f1.^2+f2.^2; H=ones(size(T)); for i=1:size(T,1) for j=1:size(T,2) t=r(i,j)/(D*D); H(i,j)=exp(-t); end end Y=fft2(double(T)); Y=fftshift(Y); Ya=Y.*H; Ya=ifftshift(Ya); I=real(ifft2(Ya)); figure(2); surf(H,Facecolor,interp,Edgecolor,none,Facelighting,phong); title(频谱图);