lena_corrupt_lp_hp.m

利用MAtlab消除噪声

%调用图像
I1=imread('f:\lena\lena_corrupt.bmp');
figure,imshow(I1)
title('hello,i am Lena')

%巴特沃思低通滤波消噪,图像模糊;理想滤波可以解决,见LenaW.M
f=double(I1); 
g=fft2(f);
g=fftshift(g);
[N1,N2]=size(g);
n=2;
d0=60;
n1=fix(N1/2);
n2=fix(N2/2);
for i=1:N1
    for j= 1:N2
        d=sqrt((i-n1)^2+(j-n2)^2);
        
        h=1/(1+0.414*(d/d0)^(2*n));
        result(i,j)=h*g(i,j);
    end
end
result=ifftshift(result);
X2=ifft2(result);
X3=uint8(real(X2));
figure,imshow(X3)
title('hello,low pass filter')

%在低通基础上，进行巴特沃思高通滤波，需要图像标定，没有解决
g2=fft2(X3);
g2=fftshift(g2);
[M1,M2]=size(g2);
d1=400;
m1=fix(M1/2);
m2=fix(M2/2);
for i=1:M1
    for j=1:M2
        d2=sqrt((i-m1)^2+(j-m2)^2);
        if d2==0
            h2==0;
        else
            h2=0.5+(1/(1+(d1/d)^(2*n)));
        end
        result2(i,j)=h2*g2(i,j);
    end
end
%标定图像
%[f1,f2]=freqspace(512,'meshgrid');
 for I = M1:M2,
             for J =  M1:M2,
              if result2(I,J)<0
                 result2(I,J)=0; 
             end
         end
     end
Y2=ifft2(result2);
Y3=uint8(real(Y2));
figure,imshow(Y3)
title('hello,high pass filter')

%直接将高通于低通图像相加，效果不理想//标定也许可以解决
X3=double(X3);
Y3=double(Y3);
Z3=X3+Y3;
Z=uint8(real(Z3));
figure,imshow(Z)
title('hello,clean clear now')
figure,imhist(Z)

%未标定的图像，直方图均衡化湿效果更差
I=histeq(Z,0:256);
figure,imshow(I)
title('hello,clean clear now,too ')
figure,imhist(I)