第三章示例

第三章

第一题

matlab结果如图

程序如下

clear;

figure

f=imread('E:\PICTRUE\Fig0432(a)(square_original).tif');

subplot(131);imshow(f);title('ԭʼͼÏñ');

[M,N]=size(f);

[f,revertclass]=tofloat(f);

F=fft2(f);

sig=10;

H=lpfilter('gaussian',M,N,sig);

G=H.*F;

g=ifft2(G);

g=revertclass(g);

subplot(132);imshow(g);

PQ=paddedsize(size(f));

Fp=fft2(f,PQ(1),PQ(2));

Hp=lpfilter('gaussian',PQ(1),PQ(2),2*sig);

Gp=Hp.*Fp;

gp=ifft2(Gp);;

gpc=gp(1:size(f,1),1:size(f,2));

gpc=revertclass(gpc)

subplot(133);imshow(gpc);title('原图');

f=imread('E:\PICTRUE\Fig0432(a)(square_original).tif');

[M,N]=size(f);

[f,revertclass]=tofloat(f);

F=fft2(f);

sig=10;

H=lpfilter('gaussian',M,N,sig);

G=H.*F;

g=ifft2(G);

g=revertclass(g);

imshow(g)

PQ=paddedsize(size(f));

Fp=fft2(f,PQ(1),PQ(2));

Hp=lpfilter('gaussian',PQ(1),PQ(2),2*sig);

Gp=Hp.*Fp;

gp=ifft2(Gp);

gpc=gp(1:size(f,1),1:size(f,2));

gpc=revertclass(gpc);

imshow(gp)

第二题

matlab结果如图

程序如下

f=imread('E:\PICTRUE\Fig0438(a)(bld_600by600).tif');

f=tofloat(f);

F=fft2(f);

S=fftshift(log(1+abs(F)));

imshow(S,[ ])

h=fspecial('sobel')

freqz2(h)

PQ=paddedsize(size(f));

H=freqz2(h,PQ(1),PQ(2));

H1=ifftshift(H);

imshow(abs(H),[ ])

figure,imshow(abs(H1),[ ])

gs=imfilter(f,h);

gf=dftfilt(f,H1);

imshow(gs,[ ])

figure,imshow(gf,[ ])

figure,imshow(abs(gs),[ ])

figure,imshow(abs(gf),[ ])

figure,imshow(abs(gs)>0.2*abs(max(gs(:))))

figure,imshow(abs(gf)>0.*abs(max(gf(:))))

 

第三题

matlab结果如图

程序如下

[U,V]=dftuv(8,5);

DSQ=U.^2+V.^2

fftshift(DSQ)

 

第四题

matlab结果如下图

程序如下

clc;

clear;

f=imread('E:\PICTRUE\Fig0441(a)(characters_test_pattern).tif');

[f,revertclass]=tofloat(f);

PQ=paddedsize(size(f));

[U,V]=dftuv(PQ(1),PQ(2));

D=hypot(U,V);

D0=0.05*PQ(2);

F=fft2(f,PQ(1),PQ(2));

H=exp(-(D.^2)/(2*(D0^2)));

g=dftfilt(f,H);

g=revertclass(g);

figure

subplot(221);imshow(f);title('');

subplot(222);imshow(fftshift(H));title(');

subplot(223);imshow(log(1+abs(fftshift(F))),[]);title('×');

subplot(224);imshow(g);title('');

 

第五题

matlab结果如图

 

 

程序如下

Hftshift(lpfilter('gaussian',500,500,50))mesh(doble(H(1:10:500,1:10:500)));

axis tight

colormap([0 0 0])

axis offw(-25,30)

view(-25,0)

 

第六题

matlab结果如图

 

程序如下

H=fftshift(hpfilter('gaussian',500,500,50));

mesh(double(H(1:10:500,1:10:500)));

axis tight

colormap([0 0 0])

axis off

figure,imshow(H,[ ])

 

H=fftshift(hpfilter('ideal',500,500,50));

mesh(double(H(1:10:500,1:10:500)));

axis tight

colormap([0 0 0])

axis off

figure,imshow(H,[ ])

 

第七题

matlab结果如图

 程序如下

f=imread('E:\PICTRUE\Fig0441(a)(characters_test_pattern).tif');

PQ=paddedsize(size(f));

D0=0.05*PQ(1);

imshow(f);title('');

H=hpfilter('gaussian',PQ(1),PQ(2),D0);

g=dftfilt(f,H);

figure,imshow(g)

第八题

matlab结果如图

程序如下

I1=imread('E:\PICTRUE\Fig0459(a)(orig_chest_xray).tif');

[len,wed]=size(I1);

g=fft2(I1);

g=fftshift(g);

[M,N]=size(g);

m=fix(M/2);

n=fix(N/2);

D0=40;

n1=2

for i=1:M

    for j=1:N

        D=sqrt((i-m)^2+(j-n)^2);

        H1=1-exp((-1)*(D^2/(2*D0^2)));

        H2=0.5+0.75*H1;

        s1(i,j)=H1*g(i,j);

        s2(i,j)=H2*g(i,j);

    end

end

I2=im2uint8(real(ifft2(ifftshift(s1)/255)));

I3=im2uint8(real(ifft2(ifftshift(s2)/255)));

I4=histeq(I3);

subplot(221),imshow(I1),title('');

subplot(222),imshow(I2),title('');

subplot(223),imshow(I3),title('');

subplot(224),imshow(I4),title('');