低通滤波的matlab实现

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/(tn+1); endendY=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(r=D0 & r(i,j)=D1 H(i,j)=(D1-r(i,j)/(D1-D0); end endendY=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); endendY=fft2(double(T);Y=fftshift(Y);Ya=Y.*H;Ya=ifftshift(Ya);I=real(ifft2(