%RGB?空間與?YCbCr?空間的互換
%實現圖像壓縮


clear
close?all;

I?=?imread（?‘avatar.bmp‘?）;
I?=?im2double（?I?）;

%RGB轉換到?YCbCr
R?=?I（?:?:?1?）;
G?=?I（?:?:?2?）;
B?=?I（?:?:?3?）;

Y?=?16?+?（?0.256789?*?R?+?0.504129?*?G?+?0.097906?*?B?）;
Cb?=?128?+?（?-0.148223?*?R?-?0.290992?*?G?+?0.439215?*?B?）;
Cr?=?128?+?（?0.439215?*?R?-?0.367789?*?G?-?0.071426?*?B?）;?



rebuilt_Cb?=?1:300;
rebuilt_Cr?=?1:300;


%圖像壓縮與解壓
for?i?=?1:2:299
???for?j?=?1:2:299
???????press_Cb?=?（?Cb（ij）+Cb（i+1j）+Cb（ij+1）+Cb（i+1j+1）?）?/?4;
???????press_Cr?=?（?Cr（ij）+Cr（i+1j）+Cr（ij+1）+Cr（i+1j+1）?）?/?4;

????????for?k?=?i:（?i?+?1?）
????????????for?l?=?j:（?j?+?1?）
????????????????rebuilt_Cb（?i?j?）?=?press_Cb;
????????????????rebuilt_Cb（?i?+?1?j?）?=?press_Cb;
????????????????rebuilt_Cb（?i?j?+?1?）?