基于MATLAB的图像压缩编码技术
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图像的压缩比计算：
>> f=imread('peppers.png');
>> imwrite(f,'peppers.png');
>> k=imfinfo('peppers.png');
>> ib=k.Width*k.Height*k.BitDepth/8;
>> cb=k.FileSize;
>> cr=ib/cb
cr =
2.0509
变换编码：
计算DCT变换的基函数：
>> n=4;
>> c=zeros(n,n);
>> for m=0:1:n-1
for k=0:1:n-1
if k==0
l=sqrt(1/n);
else
l=sqrt(2/n);
end;
c(m+1,k+1)=l*cos(((2*m+1)*k*pi)/(2*n));
end;
end;
>> colormap('gray');
>> for m=0:1:n-1
for k=0:1:n-1
subplot(n,n,m*n+k+1);
y=[zeros(m,n);zeros(1,k) 1 zeros(1,n-k-1);zeros(n-m-1,n)];
x=c*y*c';
imagesc(x);
axis square;
axis off;
end;
end;
对图像进行DCT和IDCT变换：>> rgb=imread('autumn.tif'); >> i=rgb2gray(rgb);
>> i=im2double(i);
>> i1=dct2(i);
>> i2=idct2(i1);
>> subplot(2,2,1);imshow(i);
>> subplot(2,2,2);imshow(i2);
>> subplot(2,2,3);imshow(i1);
>> subplot(2,2,4);imshow(abs(i-i2)); >> figure;mesh(i1);
>> colorbar('vert');
>> set(gcf,'color','w');
小波分析对图像进行增强处理：>> load wbarb;
>> subplot(1,2,1);image(X);
>> colormap(map);
>> axis square;
>> [c,s]=wavedec2(X,2,'sym4');
>> sizec=size(c);
>> for i=1:sizec(2)
if(c(i)>350)
c(i)=2*c(i);
else
c(i)=0.5*c(i);
end;
end;
>> xw=waverec2(c,s,'sym4'); >> subplot(1,2,2);image(xw); >> colormap(map);
>> axis square;
用二维小波分析融合图像：>> load woman;
>> X1=X;map1=map;
>> subplot(1,3,1);image(X1); >> colormap(map1);
>> axis square;
>> load wbarb;
>> X2=X;map2=map;
>> subplot(1,3,2);image(X2); >> colormap(map2);
>> axis square;
>> for i=1:256
for j=1:256
if(X2(i,j)>100)
X2(i,j)=1.25*X2(i,j);
else
X2(i,j)=0.6*X2(i,j);
end;
end;
end;
>> [c1,s1]=wavedec2(X1,2,'sym4');
>> sizec1=size(c1);
>> for i=1:sizec1(2)
c1(i)=1.25*c1(i);
end;
>> [c2,s2]=wavedec2(X2,2,'sym4');
>> c=c1+c2;
>> c=0.5*c;
>> xw=waverec2(c,s1,'sym4');
>> subplot(1,3,3);image(xw);
>> axis square;
利用图像融合法从模糊图像中恢复图像：>> load cathe_1;X1=X;
>> load cathe_2;X2=X;
>> XFUS=wfusimg(X1,X2,'sym4',5,'max','max'); >> colormap(map);
>> subplot(1,3,1);image(X1);
>> axis square;
>> subplot(1,3,2);image(X2);
>> axis square;
>> subplot(1,3,3);image(XFUS);