Compress.m

% Image compression funtion
function [comp_image_Y,comp_image_U,comp_image_V] = Compress(orig_image)

RGB=orig_image;
%下面是对RGB三个分量进行分离 
R=RGB(:,:,1);  
G=RGB(:,:,2);  
B=RGB(:,:,3); 

%RGB->YUV  
Y=0.299*double(R)+0.587*double(G)+0.114*double(B); 
[xm, xn] = size(Y);
U=-0.169*double(R)-0.3316*double(G)+0.5*double(B);  
V=0.5*double(R)-0.4186*double(G)-0.0813*double(B);  

%产生一个8*8的DCT变换举证     
T=dctmtx(8);
%进行DCT变换 BY BU BV是double类型  
BY=blkproc(Y,[8 8],'P1*x*P2',T,T');  
BU=blkproc(U,[8 8],'P1*x*P2',T,T');  
BV=blkproc(V,[8 8],'P1*x*P2',T,T');  
%低频分量量化表   
a=[
	16 11 10 16 24 40 51 61;  
	12 12 14 19 26 58 60 55;  
	14 13 16 24 40 57 69 55;  
	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;

];  
%高频分量量化表    
  b=[17 18 24 47 99 99 99 99;  
     18 21 26 66 99 99 99 99;  
     24 26 56 99 99 99 99 99;  
     47 66 99 99 99 99 99 99;  
     99 99 99 99 99 99 99 99;  
     99 99 99 99 99 99 99 99;  
     99 99 99 99 99 99 99 99;  
     99 99 99 99 99 99 99 99;];  
     
 %使用量化表对三个分量进行量化
 BY2=blkproc(BY,[8 8],'round(x./P1)',a);  
 BU2=blkproc(BU,[8 8],'round(x./P1)',b);  
 BV2=blkproc(BV,[8 8],'round(x./P1)',b);  
 
%调用压缩函数
comp_image_Y=img2jpg(BY2,1);
comp_image_U=img2jpg(BU2,2);
comp_image_V=img2jpg(BV2,3);