Giao trinh xử lý ảnh có bài tập

Gii thiu qua ti Phn I : Kin thc c bn Phn II : p dng mt s thut ton Phn III : ng dng trong h thng nhn dng mu

Gii thiu qua ti ti 23: Tm hiu v kho st ng dng ca k thut lm mnh i tng nh nh phnTun Khnh Thanh Tng

Gio vin hng dn: Nguyn Th Hong Lan Nhm sinh vin thc hin : Hong Hong

Li ni u X l nh l mt mn hc c rt nhiu ng dng trong thc t. c th vn dng cc kin thc c hc trn lp, chng em phi hon thnh mt project nht nh. Chng em chn ti "Tm hiu v kho st ng dng ca k thut lm mnh i tng nh nh phn" v thy y l mt ti rt hay, c bit c lin quan n vn phc hi v nhn dng, mt k thut rt c quan tm by gi. Chnh nh qu trnh n lc lm bi tp ln, chng em xy dng c nhng m un v tch lu c nhng kinh nghim ht sc qu bu. V v vy nn do nhn thy s lin quan, h tr ln nhau gia cc ti nn chng em xin c pht trin thm mt s tnh nng ca chng trnh bng cch tm hiu v gii quyt thm mt s ti khc. Nh vy m kh nng lm vic theo nhm ca chng em tin b r rt. Do thi gian gp rt v sp n thi k n thi, v cng cha c c kinh nghim cng nh ti liu y , nn chng em cha th hon thnh mc ch ra, tuy nhin cng thu c rt nhiu thng li ban u. Chng em xin cm n c tn tnh hng dn v dnh thi gian c bn bo co ny. Qua vic lm bi tp ln, chng em cm thy yu mn hc ny hn v quyt nh s i su tm hiu v lnh vc ny mt ngy khng xa, khi c iu kin.H Ni, ngy 15 thng 4 nm 2008

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Nhm sinh vin Hong Tun Khnh Hong Thanh Tng

Phn cng cng vic: V mc ch l trau di kin thc, chng em lun h tr v phn cng cng vic theo tiu tr c 2 cng pht trin. Tc l em v bn Tng cng tm hiu v ci t thut ton bng C, C++ hoc Java, sau tm hiu thm vic p dng vo thc t qua kt qu ca chng trnh. Nhng nu phn cng chi tit th: Hong Tun Khnh: Tm hiu k thut lm mnh nh nh phn, phn tch v tm hiu gii thut lm mnh Lu-Wang c pht trin t thut ton Zhang-Suen, ng dng ca k thut lm mnh. Hong Thanh Tng: Tm hiu k thut lm mnh nh nh phn, gii thut lm mnh song song bng gii thut Lu-Wang. C th ho bng chng trnh. Ngoi ra chng em cn tm hiu thm mt s vn khc c nu trong bi vit ny. C th ho chng trnh: Chng trnh cui cng c quyt nh vit bng Java, giao din n gin d dng, v chy thnh cng mt s gii thut ct yu. Chng trnh c cc tnh nng nh d bin, lm mnh nh nh phn, biu histogram, bin i nh mu v xm, bin i furier v cosin ri rc, ngoi ra ang pht trin thm b cng c cho php v v thao tc trc tip ln nh nh cc php ton v tr trn ma trn, nhng hin ti chng em cha c thi gian thc hin. Chng em xin gii thiu qua giao din ca chng trnh :

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Kin thc c bnX l nh l mn khoa hc cn mi m nhng ng dng kh nhiu trong thc t, c bit l h thng nhn dng. Mt h thng x l nh c bn thc hin vic thu nhn nh + phn tch nh + trch chn c tnh + lu tr phc v cho cc mc ch khc nhau. V nh trong t nhin c lng thng tin rt ln, do ta phi bit lu tr sao cho tn t dung lng m vn m bo nh lu tr c nhng c tnh c bn nht. Mun c c nh, trc tin i hi bn phi c kin thc cn bn v C, v cch t chc file. Bn cn phi bit c cc header bit dng nh, c cc pixel nh v chuyn i chng thnh d liu thch hp thc hin vic x l. Chng hn vic c nh mu bn phi bit i mu ra mc xm v sau khi thc hin x l bn i ngc li, iu ny cn mt s phn ngng chng hn nh ma trn dither. Hay vic phng to thu nh nh ch n thun l ta chn thm hng v ct hoc b i theo cch ni suy, v th khi phng to ht c nh bn thy nhng vung c duy nht mt mu, l v cc im nh ging nhau tp hp li do php chn. V d mt nh :1 2 3 4 5 6 7 8 9

phng to thnh1 1 4 4 7 7 1 1 4 4 7 7 2 2 5 5 8 8 2 2 5 5 8 8 3 3 6 6 9 9 3 3 6 6 9 9

c th hiu c bi vit ny i hi bn phi c mt kin thc c bn v x l nh trong mn hc ny, nu bit thm v ho th cng tt. Phn u tin ny s gii thiu qua v cc kin thc c bn nht, v thi gian c hn nn ch mang tnh gii thiu, bn xem li sch bit thm. Bin i nh l cch a nh t min A sang min B, sao cho c th a ngc li t B sang A, a ngc li l khi phc nh. Cc bin i hay dng l bin i furier chuyn sang min tn s hoc l kl lm gim khng gian nh trch chn c tnh qua vic lm cc tiu bnh phng (gim th nguyn). Thng thng, n gin ta ch cn hiu 2 nh l u v v, php bin i l A th : u = A*t v A* v= A u At vi At l ma trn chuyn v, cn A* l ma trn i du phn phc ca A

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Trch chn c tnh Ly bin hoc vng nh phc v cho cc mc ch nhn dng, trc khi trch chn c tnh cn ci thin nh, l cc php x l nh lc, tng tng phn... Lu tr nh c lu tr di cc mng, khi hin th th dng thut ton ct ta hin vng nh xut hin, gii thut cohen dng 4 bt t phi sang tri m ho cho v tr tri phi di trn. gim dung lng thng dng cch lu tr di dng nn, chng hn nh dng gif cho vic m ho khi lng mu ln, jpeg cho ho k xo, v nn khng mt thng tin nh huffman...

p dng mt s thut tonBin i t nh a mc xm sang nh mu Bin i Cosin ri rc Biu xm Histogram v co gin biu lm tng tng phn nh: Php lc s ci thin nh Pht hin v tch bin ng dng ca vic pht hin bin nh K thut lc Wiener Lm mnh bin cho nh nh phn Nhn dng nh Nn nh Trc tin gi s xy dng c cc lp thao tc vo ra cho chng trnh nh c file nh, da vo phn header cng bng gii m km theo ly ni dung nh, cc phng thc v nh..., v mc ch l nu cch gii quyt vn , m phng thut ton nn chng em khng nu cc lp ph ny, tp trung gii thiu nhng lp chnh.

Bin i t nh a mc xm sang nh mu

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K thut ny cn gi l k thut LUT (look up table) hin mt nh mu t nh a mc xm bn phi c mt ngng quy c trong bng no , v d vi nh 2 mu bn c th dng ngng nh sau: nu mc xm ln hn 127 cho hin thnh mu trng, nu nh hn th hin mu en Nu bn mun c 4 mu th lm nh sau : chia lm 4 ngng 0-64-128-192-255 ta c cc mu trong bng tra nh sau:ngng 1 2 3 4 mc xm en xm m xm nht trng mu en xanh vng

Mun c nhiu mu hn bn phi phn chi tit hn. hiu thm v mu bn hy nghin cu phn b v tnh bo ho. Chng hn phn b ca RGB l CYM, cho thm mu trng vo mt mu no th n s nhanh chng bo ho... Cn nu mun bin nh mu thnh nh a mc xm phc v cho vic x l nh bn lm nh sau: mt mu 32 bit chia lm 8 cm hexa, bn dng cc mt n v php dch bit tnh gi tr 2 cm mt tng ng vi cc mu, sau ly gi tr trung bnh chuyn sang mc xm. Lp ny c th thc hin nh sau://ly mu t pixel public class RGB { public static int getRed(int pix){ return (pix&0x00ff0000)>>16; } //ly mu lc t pixel public static int getGreen(int pix){ return (pix&0x0000ff00)>>8; } //ly mu lam t pixel public static int getBlue(int pix){ return pix&0x000000ff; } //tnh trung bnh public static int getColorAverage(int pixel) { int red = pixel & 0x00ff0000; int green = pixel & 0x0000ff00; int blue = pixel & 0x000000ff; return ((red >> 16) + (green >> 8) + blue) / 3; }