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DCT DefinitionBin i cosin ri rc (DCT) i din cho mt hnh nh nh l mt tng h c!" #o"ng $h%c nh"& l'n tn s*+ C%c dct2ch,c n-ng t.nh to%n chi/& h"i 0in i cosin ri rc (DCT) c!" mt hnhnh+ DCT c1 ti sn 12 mt hnh nh ti3& 0i4&2 h& ht c%c th5ng tin tr6c 7&"n %ng $4 / hnhnh l t8 tr&ng ch9 trong mt i h s* c!" c%c DCT+ : l; do nngtrong c%c ,ng d>ng n?n hnh nh+ :. d>2 DCT l @ tr&ng tAm c!" c%c th&8t to%n ti3& ch&n 7&*c ttn h"o n?n hnh nh c 0it n d'i dng EF+ (T3n n tG nh1m lm ic h%t tri4n c%c ti3&

ch&nH oint hotogr"hic E#Irts Fro&)DCT h"i chi/& c!" JK0

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Tn s* ng"ng t-ng tG tr%i s"ng hi2 t-ng tn s* dOc tG tr3n #&*ng d'i+ CV s@ ch,c n-ng c1 gi%trM $h5ng i @ h." tr3n 03n tr%i l thng c gOi l c s chc nngDC2 DCT tVng ,ngh s BUU thng c gOi l h sDC +

^&"< liChuyn i ma trn DCTC1 h"i c%ch 4 t.nh to%n DCT s= d>ng hn m/m _ c5ng c> #= l; nh+ C%c hVng h% & ti3nl 4 s= d>ng ch,c n-ng dct2+ dct2s= d>ng mt th&8t to%n d6" tr3n ``T 4 t.nh to%n nh"nh

ch1ng 'i & o l'n + hVng h% th, h"i l s= d>ng DCT bin i ma trn2 c tr li ch,cn-ng dctmtx c1 th4 c hi& 7& hVn cho c%c & o &5ng nha2 chbng hn nh [K[ hoc \K0

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Jc d c1 mt s* tn thWt / chWt lng hnh nh t%i to2 1 r rng l nh8n 0it2 mc d gn nh

[jk c%c h s* DCT c loi 0a+

Chuyn i ma trn DCTC1 h"i c%ch 4 t.nh to%n DCT s= d>ng hn m/m _ c5ng c> #= l; nh+ C%c hVng h% & ti3nl 4 s= d>ng ch,c n-ng dct2+ dct2s= d>ng mt th&8t to%n d6" tr3n ``T 4 t.nh to%n nh"nhch1ng 'i & o l'n + hVng h% th, h"i l s= d>ng DCT bin i ma trn2 c tr li ch,cn-ng dctmtx c1 th4 c hi& 7& hVn cho c%c & o &5ng nha2 chbng hn nh [K[ hoc \K0

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- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -;B2 = !"ocroc (B, +# #, (!"octrct) mt n/ .* !"octrct.data);invdct = (!"octrct) T * !"octrct.data * T;I2 = !"ocroc (B2, +# #, invdct);

im0o (I), con , im0o (I2)

Jc d c1 mt s* tn thWt / chWt lng hnh nh t%i to2 1 r rng l nh8n 0it2 mc d gn nh[jk c%c h s* DCT c loi 0a+

http://www.mathworks.com/help/toolbox/images/f21-16366.html#f21-16149

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