带阻滤波器对周期性噪声消除matlab实现

添加周期噪声

 

 参考：https://blog.csdn.net/nanhuaibeian/article/details/90343860

t=imread('ｌｕｎａ.jpg');
[m,n]=size(t);
t_1=t;
for i=1:m
for j=1:n
t_1(i,j)=t(i,j)+40*sin(40*i)+40*sin(40*j);
end
end
imshow(t),title('原图');
figure,imshow(t_1),title('加入周期噪声后');

 对周期噪声的滤波处理

I=imread('lena.jpg');
I=rgb2gray(I);
[m,n]=size(I);
J=I;
for i=1:m
    for j=1:n
        J(i,j)=I(i,j)+40*sin(20*i)+40*sin(20*j);%增加周期性噪声
    end
end
IF=fftshift(fft2(I));
JF=fftshift(fft2(J));
IF=log(1+abs(IF));
JF=log(1+abs(JF));
figure(1)
subplot(121)%显示频谱
imshow(IF,[])
subplot(122)
imshow(JF,[])
%高斯带阻滤波器构造
fbrf=ones(m,n);
for i=1:m
    for j=1:n
        fbrf(i,j)=1-exp(-0.5*(((i-m/2)^2+(j-n/2)^2-90^2)/(sqrt(i.^2+j.^2)*5))^2);%20为带阻中心，5为带宽
    end
end
 H=fbrf;
%频率域滤波
f=fftshift(fft2(J));
out=f.*H;%频率域滤波
out=ifft2(ifftshift(out));
out=abs(out);
out=out/max(out(:));%归一化【0,1】
figure(2)
subplot(121)
imshow(out,[]);
subplot(122)
imshow(J,[])