基于matlab数字图像处理之低通滤波器

基字像之通波

实践一:

理想低通滤器、Butterworth低滤波器、斯低通滤波器1.1.1理低通滤波器践代码：I=imread('couple.bmp');%I=rgb2gray(I);subplot(221),imshow(I);title('图's=fftshift(fft2(I));subplot(223),imshow(abs(s),[]);title('像里换得');subplot(224),imshow(log(abs(s)),[]);title('像里换对得谱);[a,b]=size(s);a0=round(a/2);b0=round(b/2);d=10;fori=1:aforj=1:bdistance=sqrt((i-a0)^2+(j-b0)^2);ifdistance<=dh=1;

elseh=0;end;s(i,j)=h*s(i,j);end;end;s=uint8(real(ifft2(ifftshift(s))));subplot(222),imshow(s);title('通波图);I=imread('couple.bmp');Hd=ones(size(I));Hd(r>0.2)=0;figuresurf(Hd,'Facecolor','interp','Edgecolor','none','Facelighting','phong');%画曲面色1.1.2理低通滤波器践结果截：

1.2.1Butterworth低通波器实践码：clearall;I1=imread('girl.bmp');subplot(221),imshow(I1);xlabel('(a)始像);f=double(I1);%数类型换g=fft2(f);%像里换g=fftshift(g);%叶换

F2=log(abs(g));%对傅叶结取值然取subplot(222),imshow(F2,[],'InitialMagnification','fit');%将计后阵图示colormap(jet);%色索colorbar%色索xlabel('(b)始像里变像');傅变图寸n=2;%赋始d0=5;n1=fix(N1/2);%数圆整n2=fix(N2/2);%数圆整fori=1:N1%历像forj=1:N2d=sqrt((i-n1)^2+(j-n2)^2);ifd==0h=0;elseh=1/(1+(d/d0)^(2*n));endresult(i,j)=h*g(i,j);%图像矩计理end

endF3=log(abs(result));%对傅叶变结取绝值后对subplot(223),imshow(F3,'InitialMagnification','fit');colormap(jet);%色索colorbar%色索xlabel('(c)波的叶换')result=ifftshift(result);X2=ifft2(result);X3=uint8(real(X2));subplot(224),imshow(X3)xlabel('(d)Butterworth通滤图');I1=imread('couple.bmp');[f1,f2]=freqspace(size(I1),'meshgrid');D=0.3;r=f1.^2+f2.^2;n=4;fori=1:size(I1,1)forj=1:size(I1,2)t=r(i,j)/(D*D);

Hd(i,j)=1/(t^n+1);endendsurf(Hd,'Facecolor','interp','Edgecolor','none','Facelighting','phong');%画维面色1.2.2Butterworth低通波器实践果截图：1.3.1高斯低通滤波实践代码

IA=imread('girl.bmp');[f1,f2]=freqspace(size(IA),'meshgrid');D=100/size(IA,1);r=f1.^2+f2.^2;Hd=ones(size(IA));fori=1:size(IA,1)forj=1:size(IA,2)t=r(i,j)/(D*D);Hd(i,j)=exp(-t);endendY=fft2(double(IA));Y=fftshift(Y);Ya=Y.*Hd;Ya=ifftshift(Ya);Ia=real(ifft2(Ya));figuresubplot(2,2,1),imshow(uint8(IA));title('图'subplot(2,2,2),imshow(uint8(Ia));title('斯通处);f