% ex_08_09_2.m;   習題 8.9

clear all;clc;
I=imread('girl.bmp');
subplot(2,2,1);
imshow(I);% original
 
D_20=dct2(I);
h_20=20;
D_20(abs(D_20)<h_20)=0;
IM_20=uint8(idct2(D_20));
subplot(2,2,2);
imshow(IM_20);
 
D_50=dct2(I);
h_50=50;
D_50(abs(D_50)<h_50)=0;
IM_50=uint8(idct2(D_50));
subplot(2,2,3);
imshow(IM_50);
 
D_80=dct2(I);
h_80=80;
D_80(abs(D_80)<h_80)=0;
IM_80=uint8(idct2(D_80));
subplot(2,2,4);
imshow(IM_80);