多媒体实验四 图像小波变换

实验四 图像小波变换

一、实验目的与要求： 1) 实验目的

理解

 dwt函数

 idwt函数

 wcodemat函数

 dwt2函数

 wavedec2函数

 idwt2函数

 waverec2函数

2）实验步骤

1：对图象做2-D小波分解

程序如下：

I=imread('E:111.jpg');

i=rgb2gray(I);

nbcol=size(i,1);

[cA1,cH1,cV1,cD1]=dwt2(i,'db1');

cod_X=wcodemat(i,nbcol);

cod_cA1=wcodemat(cA1,nbcol);

cod_cH1=wcodemat(cH1,nbcol);

cod_cV1=wcodemat(cV1,nbcol);

cod_cD1=wcodemat(cD1,nbcol);

dec2d=[cod_cA1,cod_cH1;cod_cV1,cod_cD1];

figure ;

subplot(1,2,1);imshow(i,[]);

subplot(1,2,2);imshow(dec2d,[]);

实验结果如下：

2：2-D小波重构

程序如下：

x=imread('E:1.jpg');

X=rgb2gray(x);

nbcol=size(X,1);

[cA1,cH1,cV1,cD1]=dwt2(X,'db1');

cod_X=wcodemat(X,nbcol);

cod_cA1=wcodemat(cA1,nbcol);

cod_cH1=wcodemat(cH1,nbcol);

cod_cV1=wcodemat(cV1,nbcol);

cod_cD1=wcodemat(cD1,nbcol);

nbcol=size(cod_X,1);

[xcA1,xcH1,xcV1,xcD1]=dwt2(cA1,'db1');

xcod_cA1=wcodemat(xcA1,nbcol);

xcod_cH1=wcodemat(xcH1,nbcol);

xcod_cV1=wcodemat(xcV1,nbcol);

xcod_cD1=wcodemat(xcD1,nbcol);

xdec2d=[xcod_cA1,xcod_cH1;xcod_cV1,xcod_cD1];

dec2d=[xdec2d,cod_cH1;cod_cV1,cod_cD1];

subplot(1,2,1);

imshow(X,[]);

subplot(1,2,2);

imshow(dec2d,[]);imshow(dec2d,[]);

实验结果如下：

3：对图象做两层分解

程序如下：

x=imread('E:111.jpg');

X=rgb2gray(x);

nbcol=size(X,111);

[cA1,cH1,cV1,cD1]=dwt2(X,'db1');

cod_X=wcodemat(X,nbcol);

cod_cA1=wcodemat(cA1,nbcol);

cod_cH1=wcodemat(cH1,nbcol);

cod_cV1=wcodemat(cV1,nbcol);

cod_cD1=wcodemat(cD1,nbcol);

nbcol=size(cod_X,111);

[xcA1,xcH1,xcV1,xcD1]=dwt2(cA1,'db1');

xcod_cA1=wcodemat(xcA1,nbcol);

xcod_cH1=wcodemat(xcH1,nbcol);

xcod_cV1=wcodemat(xcV1,nbcol);

xcod_cD1=wcodemat(xcD1,nbcol);

xdec2d=[xcod_cA1,xcod_cH1;xcod_cV1,xcod_cD1];

dec2d=[xdec2d,cod_cH1;cod_cV1,cod_cD1];

subplot(1,2,1);

imshow(X,[]);

subplot(1,2,2);

imshow(dec2d,[]);imshow(dec2d,[]);

实验结果如下：

4：对图象做两层分解重构

程序如下：

x=imread('E:111.jpg');

X=rgb2gray(x);

[c,s]=wavedec2(X,2,'sym4');

a0=waverec2(c,s,'sym4');

subplot(1,2,1);imshow(X,[]);

Title('Original Image');

subplot(1,2,2);

imshow(a0,[]);

Title('Image using idwt2');

实验结果如下：

5：图象的钝化（锐化）

程序如下：

x=imread('E:111.jpg');

X=rgb2gray(x);

blur1=X;

blur2=X;

ff1=dct2(X);

for i=1:256

for j=1:256

ff1(i,j)=ff1(i,j)/(1+(32768/(i*i+j*j))^2);

end

end

blur1=idct2(ff1);

[c,l]=wavedec2(X,2,'db3');

csize=size(c);

for i=1:csize(2);

if (abs(c(i))<300)

c(i)=c(i)*2;

else

c(i)=c(i)/2;

end

end

blur2=waverec2(c,l,'db3');

subplot(221);image(wcodemat(X,192));colormap(gray(256));title('Original Image');

subplot(222);image(wcodemat(blur1,192));colormap(gray(256));title('DCTImage');

subplot(223);image(wcodemat(blur2,192));colormap(gray(256));title('DWT Image');

blur2=waverec2(c,l,'db3');

subplot(221);image(wcodemat(X,192));colormap(gray(256));title('Original Image');

subplot(222);image(wcodemat(blur1,192));colormap(gray(256));title('DCT Image');

subplot(223);image(wcodemat(blur2,192));colormap(gray(256));title('DWT Image');

实验结果如下：

四、实验心得与感受

通过这次实验，对图像的小波变换有了深刻的认识。对小波变换有了进一步的了解。