数字图像处理--图像的傅里叶变换

figure,imshow(abs(iJP)*100);

title('相应的傅里叶反变换');

B)利用MATLAB软件实现数字图像傅立叶变换的程序B=imread('M.JPG');

I=rgb2gray(B);

imshow(I);

fftI=fft2(I);

sfftI=fftshift(fftI);

RR=real(sfftI);

II=imag(sfftI);

A=sqrt(RR.^2+II.^2);

A=(A-min(min(A)))/(max(max(A))-min(min(A)))*225;

figure;

imshow(A);

C)绘制一个二值图像矩阵,并将其傅立叶函数可视化f=zeros(30,30);

f(5:24:13:17)=1;

imshow(f,'notruesize')

F=fft2(f);

F2=log(abs(F));

figure,imshow(F2,[-1 5],'notruesize');colormap(jet);

F=fft2(f,256,256);

figure,imshow(log(abs(F)),[-1 5],'notruesize');colormap(jet);

F2=fftshift(F);

figure,imshow(log(abs(F2)),[-1 5],'notruesize');colormap(jet);

1.离散余弦变换

A)使用dct2对图像‘N.jpg’进行DCT变换。RGB=imread('N.jpg');

imshow(RGB)

I=rgb2gray(RGB);

figure,imshow(I)

J=dct2(I);

figure,imshow(log(abs(J)),[]),colormap(jet(64));colorbar;

B)将上述DCT变换结果中绝对值小于10的系数舍弃，使用idct2重构图像并

与原图像比较。

RGB=imread('N.jpg');%B

I=rgb2gray(RGB);

J=dct2(I);

figure,imshow(I);

J(abs(J)<10)=0;

K=idct2(J);

figure,imshow(K,[0 255])

J(abs(J)<10)=0;

K2=idct2(J);

figure,imshow(K2,[0 255])

C)利用DCT变换进行图像压缩。

I=imread('N.jpg');

I=im2double(I);

T=dctmtx(8);

B=blkproc(I,[8,8],'P1*x*P2',T,T');

mask=[1 1 1 1 0 0 0 0

1 1 1 0 0 0 0 0

1 1 0 0 0 0 0 0

1 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0]

B2=blkproc(B,[8 8],'P1.*x',mask);

I2=blkproc(B2,[8 8],'P1.*x*P2','T',T); imshow(I)

figure,imshow(I2)