圖像的DCT變換與反變換.doc

ticclose allI=imread(D:MATLABtuxiangmessi.bmp); %該圖片在安裝matlab的目錄中找I=rgb2gray(I); %將該圖片轉(zhuǎn)換為灰度圖象I=im2double(I); %圖像存儲(chǔ)類型轉(zhuǎn)換% T=dctmtx(8); %離散余弦變換矩陣p,q=size(I);T = zeros(8,8);for i=0:7 for j=0:7 if (i=0) T(i+1,j+1)=1/sqrt(8); else T(i+1,j+1)=sqrt(2/8)*cos(pi*(2*j+1)*i/(2*8); end endendB=blkproc(I,8 8,P1*x*P2,T,T); %對(duì)原圖像進(jìn)行DCT變換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); %用mask進(jìn)行數(shù)據(jù)壓縮，丟棄右下角高頻數(shù)據(jù)I2=blkproc(B2,8 8,P1*x*P2,T,T);%進(jìn)行DCT反變換未經(jīng)量化，得到壓縮后的圖像tables=16 11 10 16 24 40 51 61 12 12 14 19 26 58 60 55 14 13 16 24 40 57 69 56 14 17 22 29 51 87 80 62 18 22 37 56 68 109 103 77 24 35 55 64 81 104 113 92 49 64 78 87 103 121 120 101 72 92 95 98 112 100 103 99;B3=blkproc(B,8 8,x./P1,tables); %系數(shù)進(jìn)行亮度量化I3=blkproc(B3,8 8,P1*x*P2,T,T);%進(jìn)行DCT反變換且經(jīng)量化，得到壓縮后的圖像mask1=1 1 1 1 1 0 0 0 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;B4=blkproc(B,8 8,P1.*x,mask1); %用mask1進(jìn)行數(shù)據(jù)壓縮，丟棄右下角高頻數(shù)據(jù)I4=blkproc(B4,8 8,P1*x*P2,T,T);%進(jìn)行DCT反變換未經(jīng)量化，得到壓縮后的圖像imshow(I)title(原始圖像)figure;imshow(B)title(DCT變換后的圖像)figure;imshow(B3)title(DCT變換后量化的圖像)figure;imshow(I2)title(經(jīng)mask壓縮后的圖像)figure;imshow(I3)title(經(jīng)量化壓縮后的圖像)figure;imshow(I4)title(經(jīng)mask1壓縮后的圖像)%信噪比的計(jì)算mse=0; %mseb原圖與處理圖像的均方誤差for i=1:p for j=1:q a=(I(i,j)-I2(i,j)2; mse=mse+a; endendmse=mse/(256*256);psnr=(20*log2(255)-10*log2(mse)/log2(10)mse=0; %mseb原圖與處理圖像的均方誤差for i=1:p for j=1:q a=(I(i,j)-I3(i,j)2; mse=mse+a; endendmse=mse/(256*256);psnr1=(20*log2(255)-10*log2(mse)/log2(10)mse=0; %mseb原圖與處理圖像的均方誤差for i=1:p for j=1:q a=(I(i,j)-I4(