pinyuzengqiang.m

在频域对指纹图像进行增强

clc
 %[I,map]=imread('cameraman.tif');
[I,map]=imread('wen.jpg');
 %I=rgb2gray(I1);
%[I,map]=imread('37_3.bmp');
noisy=imnoise(I,'gaussian',0.01);
imshow(noisy,map);
[M N]=size(I);
F=fft2(double(noisy));
fftshift(F);
Dcut=35;
D0=650;
D1=750;
for u=1:M
    for v=1:N
    D(u,v)=sqrt(u^2+v^2);
    BUTTERH(u,v)=1/(1+(sqrt(2)-1)*(D(u,v)/Dcut)^2);
    EXPOTH(u,v)=exp(log(1/sqrt(2))*(D(u,v)/Dcut)^2);
      if D(u,v)<D0
         TRAPEH(u,v)=1;
      elseif  D(u,v)<=D1
         TRAPEH(u,v)=( D(u,v)-D1)/(D0-D1);
      else
         TRAPEH(u,v)=0;
      end
    end 
end 
BUTTERG=BUTTERH(u,v).*F;
BUTTERfiltered=ifft2(BUTTERG);
EXPOTG=EXPOTH(u,v).*F;
EXPOTfiltered=ifft2(EXPOTG);
TRAPEG=TRAPEH(u,v).*F;
TRAPEfiltered=ifft2(TRAPEG);
subplot(2,2,1),imshow(noisy)
subplot(2,2,2),imshow(BUTTERfiltered)
subplot(2,2,3),imshow(EXPOTfiltered)
subplot(2,2,4),imshow(TRAPEfiltered)