基于matlab的Butterworth低通滤波程序分享

piday123

clear all;

0 Z* G0 e, Q+ R+ Y% K+ Rclose all;
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5 G* ?" M# J" NP=input('inputimage data:');
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d=size(P);

if(d(3)>1)
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# y; g( z  W& x/ Z    P=rgb2gray(P);
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3 w0 C; S- _3 N4 j- Tend
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subplot(131);imshow(P);
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title('原始图像');
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P1=imnoise(P,'salt& pepper',0.02);

subplot(132)
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imshow (P1);

3 B7 L; H) H4 L$ F/ ptitle('加入椒盐噪声后的图像');
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f=double(P1);

$ `" e) C! [- \6 N" Sg=fft2(f);%傅里叶变换
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g=fftshift(g);%转换数据矩阵fftshift是针对频域的，将FFT的DC分量移到频谱中心
即对频域的图像，

[M,N]=size(g);

% |  G/ ?- q* i5 ^* k( f  f4 r( FD0=input('inputnonnegative dhreshold D0=');

n=input('input theorder of filtering n=');

n1=fix(M/2);
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7 v: w$ C7 R0 Qn2= fix(N/2);

for i=1:M

- \8 Z  ^) C9 y3 @    for j=1:N

+ O3 g  h4 O7 I4 p1 N2 m# T        d=sqrt((i-n1)^2+(j-n2)^2);

h=1/(1+(d/D0)^(2*n));

' R8 u2 U( |$ g& ^        result(i,j)=h*g(i,j);

    end
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8 V3 }8 _+ |' {end

result=ifftshift(result);
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' s/ W" o6 v- T3 YX2=ifft2(result);

& V& U7 i- W* d, W$ D! Z7 {X3=uint8(real(X2));
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1 ~  {/ W( @: v* r6 Jsubplot(133)
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imshow (X3);
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# I( \; e! A; ]) ftitle('Butterworth低通滤波所得图像');
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基于matlab的Butterworth低通滤波程序