clc;
clear?all;
I?=?imread（‘cameraman.tif‘）;
I1=I;
[row?coln]=?size（I）;
I=?double（I）;
%---------------------------------------------------------
%?Subtracting?each?image?pixel?value?by?128?
%--------------------------------------------------------
I?=?I?-?（128*ones（256））;

quality?=?input（‘What?quality?of?compression?you?require?-?‘）;

%----------------------------------------------------------
%?Quality?Matrix?Formulation
%----------------------------------------------------------
Q50?=?[?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];
?
?if?quality?>?50
?????QX?=?round（Q50.*（ones（8）*（（100-quality）/50）））;
?????QX?=?uint8（QX）;
?elseif?quality??????QX?=?round（Q50.*（ones（8）*（50/quality）））;
?????QX?=?uint8（QX）;
?elseif?quality?==?50
?????QX?=?Q50;
?end
?
?
?
?
%----------------------------------------------------------
%?Formulation?of?forward?DCT?Matrix?and?inverse?DCT?matrix
%----------------------------------------------
DCT_matrix8?=?dct（eye（8））;
iDCT_matrix8?=?DCT_matrix8‘;???%inv（DCT_matrix8）;




%----------------------------------------------------------
%?Jpeg?Compression
%----------------------------------------------------------
dct_restored?=?zeros（rowcoln）;
QX?=?double（QX）;
%----------------------------------------------------------
%?Jpeg?Encoding
%----------------------------------------------------------
%----------------------------------------------------------
%?Forward?Discret?Cosine?Transform
%----------------------------------------------------------

for?i1=[1:8:row]
????for?i2=[1:8:coln]
????????zBLOCK=I（i1:i1+7i2:i2+7）;
????????win1=DCT_matrix8*zBLOCK*iDCT_matrix8;
????????dct_domain（i1:i1+7i2:i2+7）=win1;
????end
end
%-----------------------------------------------------------
%?Quantization?of?the?DCT?coefficients
%-----------------------------------------------------------
for?i1=[1:8:row]
????for?i2=[1:8:coln]
????????win1?=?dct_domain（i1:i1+7i2:i2+7）;
????????win2=round（win1./QX）;
????????dct_quantized（i1:i1+7i2:i2+7）=win2;
????end
end




%-----------------------------------------------------------
%?Jpeg?Decoding?
%-----------------------------------------------------------
%?Dequantization?of?DCT?Coefficients
%-----------------------------------------------------------
for?i1=[1:8:row]
????for?i2=[1:8:coln]
????????win2?=?dct_quantized（i1:i1+7i2:i2+7）;
????????win3?=?win2.*QX;
????????dct_dequantized（i1:i1+7i2:i2+7）?=?win3;
????end
end
%-----------------------------------------------------------
%?Inverse?DISCRETE?COSINE?TRANSFORM
%-----------------------------------------------------------
for?i1=[1:8:row]
????for?i2=[1:8:coln]
????????win3?=?dct_dequantized（i1:i1+7i2:i2+7）;
????????win4=iDCT_matrix8*win3*DCT_ma

?屬性????????????大小?????日期????時間???名稱
-----------?---------??----------?-----??----
?????文件????????3538??2012-10-06?06:46??jpegimplementation.m
?????文件????????1321??2014-02-12?14:09??license.txt