RGB=imread（‘lena.jpg‘）;%讀取圖片
RGB=imresize（RGB[168224]）;%因為1.jpg大小為169*220，所以我改為168*224
imwrite（RGB‘start.jpg‘）;?%保存壓縮前圖像
%下面是對RGB三個分量進行分離此時他們依然為整數(shù)
R=RGB（::1）;
G=RGB（::2）;
B=RGB（::3）;
%RGB->YUV
Y=0.299*double（R）+0.587*double（G）+0.114*double（B）;
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）;
YUV=cat（3YUV）;%YUV圖像
figureimshow（uint8（YUV））title（‘YUV‘）

%T=dctmtx（8）;%產(chǎn)生一個8*8的DCT變換舉證
n?=?8;
[ccrr]?=?meshgrid（0:n-1）;
T?=?sqrt（2?/?n）?*?cos（pi?*?（2*cc?+?1）?.*?rr?/?（2?*?n））;
T（1:）?=?T（1:）?/?sqrt（2）;
%進行DCT變換?BY?BU?BV是double類型
BY=blkproc（Y[8?8]‘P1*x*P2‘TT‘）;
BU=blkproc（U[8?8]‘P1*x*P2‘TT‘）;
BV=blkproc（V[8?8]‘P1*x*P2‘TT‘）;

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;];?%量化值
??
??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;];
???
???%BY2?BU2?BV2是double類型
???BY2=blkproc（BY[8?8]‘x./P1‘a(chǎn)）;
???BU2=blkproc（BU[8?8]‘x./P1‘b）;
???BV2=blkproc（BV[8?8]‘x./P1‘b）;