%	Author: Xiaofeng Xu, Polytechnic University  4/21/2002
%This function calls for another function "quan_dct.m"

%Read Image File
Img= imread('slena256.bmp');

%DCT Transform
Img_dct=blkproc(Img,[8 8],'dct2');
%Quantization
QImg_dct=blkproc(Img_dct,[8 8],'quan_dct',0.5);
%Inverse DCT Transform
RImg=blkproc(QImg_dct,[8 8],'idct2');
%Show Reconstruction Image
figure;
imshow(uint8(RImg));

%DCT Transform
Img_dct=blkproc(Img,[8 8],'dct2');
%Quantization
QImg_dct=blkproc(Img_dct,[8 8],'quan_dct',1);
%Inverse DCT Transform
RImg=blkproc(QImg_dct,[8 8],'idct2');
%Show Reconstruction Image
figure;
imshow(uint8(RImg));

%DCT Transform
Img_dct=blkproc(Img,[8 8],'dct2');
%Quantization
QImg_dct=blkproc(Img_dct,[8 8],'quan_dct',2);
%Inverse DCT Transform
RImg=blkproc(QImg_dct,[8 8],'idct2');
%Show Reconstruction Image
figure;
imshow(uint8(RImg));

%DCT Transform
Img_dct=blkproc(Img,[8 8],'dct2');
%Quantization
QImg_dct=blkproc(Img_dct,[8 8],'quan_dct',4);
%Inverse DCT Transform
RImg=blkproc(QImg_dct,[8 8],'idct2');
%Show Reconstruction Image
figure;
imshow(uint8(RImg));

%DCT Transform
Img_dct=blkproc(Img,[8 8],'dct2');
%Quantization
QImg_dct=blkproc(Img_dct,[8 8],'quan_dct',8);
%Inverse DCT Transform
RImg=blkproc(QImg_dct,[8 8],'idct2');
%Show Reconstruction Image
figure;
imshow(uint8(RImg));

%DCT Transform
Img_dct=blkproc(Img,[8 8],'dct2');
%Quantization
QImg_dct=blkproc(Img_dct,[8 8],'quan_dct',16);
%Inverse DCT Transform
RImg=blkproc(QImg_dct,[8 8],'idct2');
%Show Reconstruction Image
figure;
imshow(uint8(RImg));