Công nghệ nén ảnh JPEG, chuẩn JPEG và các loại JPEG. Thử nghiệm trên ứng dụng cụ thể

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ti: Cng ngh nn nh JPEG, chun JPEG v cc loi JPEG. Th nghim trn ng dng c th Sinh vin thc hin: 1. Phm Chin Thng MSSV: 20082485 2. inh c Tn MSSV: 20082311 3. Nguyn Mnh Hong MSSV: 20081088 Gio vin hng dn: Nguyn Th Hong Lan

H NI 2010

MC LC1. M U...tr32. NI DUNG...tr31. Cng ngh JPEG...tr31. JPEG l g.tr31. Phng php nn nh JPEG...tr35. Khi qut v phng php nn nh tnh.tr35. Phng php nn nh theo chun JPEG.tr55. u nhc imt ca phng php nn nh JPEG....tr111. Chun JPEG...tr121. Cc loi JPEG.tr161. JPEG 1992..tr161. LS JPEG .tr161. JPEG 2000..tr181. JPEG searchtr221. JPEGXR..tr221. Th nghim ng dng..tr2314. KT LUN..tr2915. DANH MC TI LIU THAM KHO...tr30

1. M U.Cng vi s pht trin mnh m ca my tnh v s ra i ca Internet th vic tm mt phng php nn nh gim bt khng gian lu tr thng tin v truyn thng tin trn mng nhanh chng ang l mt yu cu cn thit. Trong nhng nm gn y, c rt nhiu cc phng php v ang c nghin cu rng ri thc hin nn nh. Tt c u vi mt mc ch chung l lm th no biu din mt nh vi dung lng t nht c th ti thiu ho dung lng knh truyn v khng gian lu tr trong khi vn gi c tnh trung thc ca nh. V JPEG l mt trong nhng phng php nn nh kh hiu qu. Trong ti ny chng ta cung nghin cu v Cng ngh nn nh JPEG, chun JPEG v cc loi JPEG. Th nghim trn ng dng c th1. NI DUNG.1. CNG NGH JPEG.1. JPEG l g?JPEGvit tt ca Joint Photographic Experts Group, mt nhm cc nh nghin cu pht minh ra nh dng ny hin th cc hnh nh y mu hn (full-colour) cho nh dng di ng m kch thc file li nh hn. y l mt phng php nn nh hiu qu, n cho php lm vic vi cc nh c nhiu mu v kch c ln, t l nn nh t mc so snh ti vi chc ln (ch khng phi phn trm).1. Phng php nn nh JPEG.20. Khi qut v phng php nn nh tnhC nhiu cch nn nh, nhng da vo yu t bo ton thng tin c th phn chia thnh 2 phng php nn nh tnh, l:1. Nn khng mt mt thng tin: s dng cc phng php m ha d liu1. Nn c mt mt thng tin: Phng php nn da trn php bin i nhQu trnh nn nh c m t theo s :

Cc phng php m ha d liu c th k n:1. M hang lot(RLE): Dng s m thay th cc c dim ging nhau lp li.1. M Shannon-Fano: Dng cc cm bt c di thay i m ha1. M Huffman: S dng cc c im m ha ca Shannon-Fano vi tng: K hiu c kh nng xut hin nhiu c t m ngn.1. M Lemple- Ziv: Da trn vic xy dng v tra t in1. M d on: Da trn qu trnh to im tun t v lut d on.Cc php bin i p dng trong nn nh bao gm: 1. Php bin i Cosin ri rc(DCT): Biu din cc gi tr im nh trn min tn s, tp trung nng lng vo mt s h s. DCT s dng trong cc chun JPEG v MPEG1. Php bin i Wavelet ri rc(DWT): s dng cc b lc thng di x l phn tch a phn trong php DWT.1. Php bin i Fractal: S dng cc php bin i hnh hc.Nn nh tnh da trn php bin i nh c m t trong s :

30. Phng php nn nh theo chun JPEG1. Php bin i DCT (Discrete Cosin Transform) Nh chng ta ni trn, php bin i DCT c s dng trong phng php nn nh theo chun JPEG. V vy trc khi i vo tm hiu v phng php nn nh JPEG chng ta cng khi qut s qua v php bin i DCT.

1. Phng php nn nh theo chun JPEG Phng php nn nh theo thun JPEG c th cho h s nn ti 80:1 hay ln hn, nhng bn phi chu mt thng tin (nh sau khi bung nn khc vi nh ban u), lng thng tin mt mt tng dn theo h s nn. Tuy nhin s mt mt thng tin ny khng b lm mt cch cu th. JPEG tin hnh sa i thng tin nh khi nn sao cho nh mi gn ging nh nh c, khin phn ng mi ngi khng nhn thy s khc bit. V bn hon ton c th qun l s mt mt ny bng cch hn ch h s nn. Nh th ngi dng c th cn nhc gia ci li ca vic tit kim b nh v mc mt thng tin ca nh, chn phng n thch hp.

Phng php nn nh JPEG da trn nguyn l sau: nh mu trong khng gian ca 3 mu RGB (red Green Blue) c bin i v h YUV (hay YCBCr) (iu ny khng phi l nht thit, nhng nu thc hin th cho kt qu nn cao hn) theo cng thc :YUV. = 0.615R 0.515G 0.100BY= 0.299R + 0.587G + 0.114BU= 0.492(B Y)= = 0.147R 0.289G + 0.436BV= 0.877(R Y)H YUV l kt qu nghin cu ca cc nh sn xut v tuyn truyn hnh h Pal, Secam v NTSC, nhn thy tn hiu video c th phn ra 3 thnh phn Y, U, V (cng nh phn theo mu chun , xanh l cy v xanh da tri). V mt iu th v l h nhn th ca con ngi rt nhy cm vi thnh phn Y v km nhy cm vi hai loi U v V. Phng php JPEG nm bt pht hin ny tch nhng thng tin tha ca nh. H thng nn thnh phn Y ca nh vi mc t hn so vi U, V, bi ngi ta t nhn thy s thay i ca U v V so vi Y. Giai on tip theo l bin i nhng vng th hin dng bin i cosin ri rc (thng thng l nhng vng 8x8 pixel). Khi thng tin v 64 pixel ban u s bin i thnh ma trn c 64 h s th hin "thc trng" cc pixel. iu quan trng l y h s u tin c kh nng th hin "thc trng" cao nht, kh nng gim rt nhanh vi cc h s khc. Ni cch khc th lng thng tin ca 64 pixel tp trung ch yu mt s h s ma trn theo bin i trn. Trong giai on ny c s mt mt thng tin, bi khng c bin i ngc chnh xc. Nhng lng thng tin b mt ny cha ng k so vi giai on tip theo. Ma trn nhn c sau bin i cosin ri rc c lc bt s khc nhau gia cc h s. y chnh l lc mt nhiu thng tin v ngi ta s vt b nhng thay i nh ca cc h s. Nh th khi bung nh nn bn s c c nhng tham s khc ca cc pixel. Cc bin i trn p dng cho thnh phn U v V ca nh vi mc cao hn so vi Y (mt nhiu thng tin ca U v V hn). Sau th p dng phng php m ha ca Hoffman: Phn tch dy s, cc phn t lp li nhiu c m ha bng k hiu ngn (marker). (1)(2)Vi v

Khi bung nh ngi ta ch vic lm li cc bc trn theo qu trnh ngc li cng vi cc bin i ngc.

V phng php ny thc hin vi cc vng nh (thng thng l 8 x 8 pixel) nn hay xut hin s mt mt thng tin trn vng bin ca cc vng (block) ny. Hin nay ngi ta gii quyt vn ny bng cch lm trn nh sau khi bung nn che lp s khc bit ca bin gii gia cc block. Mt h nn nh theo chun JPEG cng algorithm lm trn nh c cng ty ASDG a ra trong h Art Department Professional.

Hnh nhCht lngKch thc (byte)T s nnBnh lun

Cht lng rt cao (Q = 100)83,2612.6:1Cc im nh cc k nh

Cht lng trung bnh (Q = 50)15,13815:01Du hiu ban u ca cc im nh

Va cht lng (Q = 25)9,55323:01To tc mnh m hn; mt thng tin phn gii cao

Cht lng thp (Q = 10)4,78746:1Tn tht nghim trng v bin gia cc vng nh

Thp nht cht lng (Q = 1)1,523144:1Phn m rng mt mu sc v chi tit, cc l gn nh khng th nhn ra

2.3 u nhc im ca phng php nn nh JPEG.a. u im: JPEG cho php nn nh vi t s nn ln n 80:1 hoc cao hn, hin th cc hnh nh y mu hn (full-colour) cho nh dng di ng m kch thc file li nh hn. JPEG cng c s dng rt nhiu trn Web. Li ch chnh ca chng l chng c th hin th cc hnh nh vi mu chnh xc true-colour (chng c th ln n 16 triu mu), iu cho php chng c s dng tt nht cho cc hnh nh chp v hnh nh minh ha c s lng mu ln.1. Nhc im.Nhc im chnh ca nh dng JPEG l chng c nn bng thut tonlossy (mt d liu). iu ny c ngha rng hnh nh ca bn s b mt mt s chi tit khi chuyn sang nh dng JPEG. ng bao gia cc khi mu c th xut hin nhiu im m, v cc vng s mt s r nt, t s nn cng cao th s mt mt thng tin trn nh JPEG cng ln. Ni mt cch khc, nh dng JPEG thc hin bo qun tt c thng tin mu trong hnh nh , tuy nhin vi cc hnh nh cht lng mu cao high-colour nh hnh nh chp th iu ny s khng h hn g.Cc nh JPEG khng th lm trong sut hoc chuyn ng - trong trn hp ny bn s s dng nh dng GIF (hoc nh dng PNG to trong sut).

1. CHUN JPEGJoint Photographic Experts Group - tiu chun cng b v c pht trin

Tn thng gpPhnNm cng bISO / IEC sS ITUCch thc thc hin

JPEGPhn 11992ISO / IEC 10918-1ITU-T Rec.T.81nn k thut s v m ha lin tc mu sc ca hnh nh da theo cc iu kin v nguyn tc.

Phn 21994ISO / IEC 10918-2ITU-T Rec.T.83nn k thut s v m ha lin tc mu sc ca hnh nh - da theo cc th nghim.

Phn 31996ISO / IEC 10918-3ITU-T Rec.T.84nn k thut s v m ha lin tc mu sc ca hnh nh: m rng thm.

Phn 41998ISO / IEC 10918-4ITU-T Rec.T.86nn k thut s v m ha lin tc mu sc ca hnh nh: cu hnh ng k ca JPEG, cu hnh SPIFF, th SPIFF, khng gian mu SPIFF, APPn nh du, cc dng nn SPIFF

Phn 5Km pht trinISO / IEC 10918-5 FCDnn k thut s v m ha lin tc mu sc ca hnh nh: JPEG File Interchange Format (JFIF)

JPEG-LSPhn 11998ISO / IEC 14495-1ITU-T Rec.T.87Khng tn tht v gn nh gi c mu sc c bn ca hnh nh.

Phn 22002ISO / IEC 14495-2ITU-T Rec.T.870Khng tn tht v gn nh gi c mu sc ca ton b bc nh.

JPEG 2000Phn 12000ISO / IEC 15444-1ITU-T Rec.T.800H thng m ha hnh nh JPEG 2000- Nng ct ca h thng m ha.

Phn 22004ISO / IEC 15444-2ITU-T Rec.T.801H thng m ha hnh nh JPEG 2000 thm phn m rng

Phn 32002ISO / IEC 15444-3ITU-T Rec.T.802H thng m ha hnh nh JPEG 2000: Motion JPEG 2000

Phn 42002ISO / IEC 15444-4ITU-T Rec.T.80H thng m ha hnh nh JPEG 2000: kim tra s ph hp

Phn 52003ISO / IEC 15444-5ITU-T Rec.T.804H thng m ha hnh nh JPEG 2000: phn mm c lin quan

Phn 62003ISO / IEC 15444-6H thng m ha hnh nh JPEG 2000: nh dng phc hp cho tp tin hnh nh.

Phn 82007ISO / IEC 15444-8ITU-T Rec.T.807H thng m ha hnh nh JPEG 2000: Bo mt JPEG 2000

Phn 92005ISO / IEC 15444-9ITU-T Rec.T.808H thng m ha hnh nh JPEG 2000: Tng tc cng c, API v giao thc

Phn 102008ISO / IEC 15444-10ITU-T Rec.T.809H thng m ha hnh nh JPEG 2000: Phn m rng cho d liu ba chiu

Phn 112007ISO / IEC 15444-11ITU-T Rec.T.810H thng m ha hnh nh JPEG 2000: khng dy

Phn 122004ISO / IEC 15444-12H thng m ha hnh nh JPEG 2000: cn c theo tiu chun ISO nh dng tp tin truyn thng

Phn 132008ISO / IEC 15444-13ITU-T Rec.T.812H thng m ha hnh nh JPEG 2000: Mt mc nhp cp b m ha JPEG 2000

Phn 14Km pht trinISO / IEC 15444-14 AWIH thng m ha hnh nh JPEG 2000: c cu XML i din v tham kho

MRC1999ISO / IEC 16485ITU-T Rec.T.44pha trn cc lp ni dung

JPSearchPhn 12007ISO / IEC TR 24800-1JPSearch: H thng khung v cc thnh phn

Phn 2Km pht trinISO / IEC 24800-2 FCDJPSearch: ng k, nhn dng v qun l cc lc v bn th

Phn 32010ISO / IEC 24800-3JPSearch: truy vn dng

Phn 4Km pht trinISO / IEC 24800-4 FCDJPSearch: nh dng tp tin cho cc siu d liu nhng vo d liu hnh nh (JPEG v JPEG 2000)

Phn 5Km pht trinISO / IEC 24800-5 FCDJPSearch: trao i d liu gia cc kho lu tr hnh nh nh dng

Phn 6Km pht trinISO / IEC 24800-6 NPJPSearch:cc phn mm lin quan

JPEG XRPhn 1Km pht trinISO / IEC 29199-1 DTRh thng m ha hnh nh JPEG XR: H thng kin trc

Phn 22009ISO / IEC 29199-2ITU-T Rec.T.832h thng m ha hnh nh JPEG XR: Hnh nh c t k thut m ha

Phn 3Km pht trinISO / IEC 29199-3 FDISh thng m ha hnh nh JPEG XR:trao i qua li ga cc dng JPEG XR

Phn 42010ISO / IEC 29199-4ITU-T Rec.T.834h thng m ha hnh nh JPEG XR: kim tra s ph hp

Phn 52010ISO / IEC 29199-5ITU-T Rec.T.835h thng m ha hnh nh JPEG XR: cc phn mm lin quan

AICKm pht trinISO / IEC 29170 NPm ha nng cao v cc phng php nh gi

1. CC LOI JPEG1.JPEG(1992):L loi JPEG chun c ni trn.2.LS-JPEG( Lossness JPEG)LS-JPEG c pht trin nh s b sung mun mng cho JPEG vo nm 1993,bng cch s dng 1 k thut khc nhau t tiu chun JPEG c.N s dng 1 h thng d bo c sp xp da trn ba im ln cn( upper,left and upper-left) v entropy m ha da trn cc li d bo.Khng ging nh ch mt d liu da trn DCT, cc qu trnh m ha khng mt mt thng tin da trn m hnh tin on m n gin gi l chuyn m xung vi sai(Differential Pulse Code Modulation-DPCM) . y l mt m hnh d on cc gi tr mu t cc mu ln cn c m ha trong hnh nh .Hu ht cc d on ly trung bnh ca cc mu ngay lp tc bn trn v bn tri ca mu mc tiu.DPCM m ha s khc bit gia cc mu d on thay v mi mu m ha c lp.S khc bit t mt trong nhng mu tip theo thng l gn bng khng. Cc bc chnh ca ch hot ng khng gim cht lng c m t trong Hnh 2

Trong qu trnh ny, d bo cc kt hp ti a ba mu ln cn ti A, B, v C c th hin trong hnh 3 d bo gi tr ca mu ti v tr dn nhn ca X. Ba mu lng ging phi c c d on mu . Bt k mt trong nhng d on cho thy trong bng di y c th c s dng c tnh mu t ti . Bt k mt trong tm d on c lit k trong bng c th c s dng. Lu rng cc la chn 1, 2, v 3 c d on mt chiu v la chn 4, 5, 6, v 7 c d on hai chiu. Gi tr la chn u tin trong bng, bng khng, ch c s dng m ha khc bit ch phn cp hot ng. Mt khi tt c cc mu c d on, s khc bit gia cc mu c th c ly v entropy-m ha trong mt thi trang khng gim cht lng bng cch s dng m ha Huffman hoc m s hc .Thut ton LoCo-ICt li ca LS-JPEG da trn cc thut ton LoCo-I.Trong thut ton LoCo-I, cnh c pht hin ban u ca cc cnh theo chiu ngang hoc chiu dc bng cch kim tra cc im nh ln cn ca im nh X hin thi nh trong hnh 3.Cc im nh c nhn B c s dng trong trng hp ca cnh thng ng trong khi im c nhn A s dng trong trng hp cnh ca cnh nm ngang.iu d on n gin ny c gi l pht hin cnh trung v(Median Edge Dectection-MED) hay d on LoCo-I(LoCo-I predictor) im nh X c d on bng LoCo-I predictor theo tiu ch sau y:Ba d on n gin c chn theo cc iu kin:(1) n c khuynh hng nhn B trong trng hp tn ti cnh dc tri ca X,(2) A trong trng hp cnh nm ngang pha trn, hoc (3) A+B-C nu khng c cnh no c pht hin. 3.JPEG 2000Nh trnh by, k thut nn JPEG s lm mt thng tin lc gii nn, cng nn vi h s cao th thng tin cng mt nhiu khi bung. V vy gii quyt vn ny, thng 12/1999 mt bn phc tho tiu chun nn hnh nh theo cng ngh mi JPEG2000. Thng 8/2000, bn phc tho v tiu chun JPEG2000 c lu hnh trong gii chuyn gia hnh nh. Sau n c cng nhn l tiu chun quc t vo thng 12/2000 v c ISO hp thc ha nm nay cho php ng dng vo cc h x l, phn phi.Vi JPEG2000 k thut x l hnh nh s t c nhng kt qu rt ngon mc v c th nn nh t 100-200 ln m hnh nh khng sai st bao nhiu so vi hnh nh gc. Nhng u l im khc bit k thut JPEG2000 vt tri hn hn so vi JPEG?JPEG2000 l h thng m ha hnh nh m k thut nn da trn k thut sng ngn. L mt tin ch ton hc cho php m t bng mt cng thc n gin nhng g xy ra ti mt thi im chnh xc ca tn hiu. Vi mt chui sng ngn, ch cn biu din bng vi cng thc, ng biu din khng u m khng cn phi m t c tnh ca tng im mt. V l d nhin s rt c lc khi phn tch t m mt file nh k thut s.Thut ton trong k thut JPEG2000 l chn mt s nh cc sng ngn, cc sng ny c lp li nhng ni khc nhau, t l khc nhau m t chnh xc tn hiu ca hnh nh. File nh nn khng cha nhiu hn s lng ch v tr v gin n ca tng sng ngn. V k thut m ha theo tng khi, theo tng khu vc u tin ca hnh nh (ROI -Regional Of Interest) c p dng cng l mt tin b ng k trong thut ton m ha JPEG2000.

Cc im ch trong JPEG20003.1-S thay i cc thnh phn muBan u hnh nh phi c chuyn i t khng gian mu RGB sang khng gian mu khc, dn n s tch bit ca 3 thnh phn mu ny.C 2 s la chn: a.Khng th o mu(Irreversible Color Transform -ICT): s dng khng gian mu YC B C R b.C th o mu(Reversible Color Transform-RCT):s dng khng gian mu YUV sa i m khng thc hin cc li lng t cho nn n c th o mu. Thc hin ng cc yu cu RCT tc l s c lm trn theo quy nh m khng th c th hin chnh xc di dng ma trn. Qu trnh chuyn i l:

3.2-Lt(Tiling)Sauk hi chuyn i mu sc,bc nh c phn chia-gi l cc lt,cc vng vung ca nh c chuyn i v m ha ring bit nhau.Lt c nhiu kch c, v n c th coi cc lt ca nh nh 1 lt duy nht.Khi kch thc c chn, tt c cc lt s c cng kch thc(ngoi tr nhng lt bn phi v pha di ng bao).Vic chia hnh nh thnh nhu lt l c li,cc b gii m cn t b nh hn gii m bc nh v n c th la chn ch gii m lt c chn gii m 1 phn ca bc nh.Bt li ca phng php ny l cht lng hnh nh gim thp hn tn hiu tt nht n t s truyn( peak signal to noise ratio). S dng nhiu lt c th to khi nh hng ging chun JPEG 1992.3.3-Hm bin thin chuyn i(Wavelet Trasform)Nhng lt ny sau c bin i n su ty ,tri vi JPEG 1992-s dng bin i cosin vng nh kch thc 8x8 :JPEG 2000 s dng 2 bin i wavelet 1.Khng th o ngc: n c gi l khng th o bi n s dng k thut lng t ha ph thuc vo chnh xc ca b gii m. 2.o ngc:N ch s dng h s nguyn,cho nn u ra khng yu cu lm trn s(lng t) v v vy n khng thc hin bt k sai s lng t no.N c s dng trong m ha khng mt mt thng tin.3.4-Lng t ha(Quantization )Sau khi bin i wavelet transform,cc h s l v hng- c lng t ha gim s lng cc bit ,ti cc im tn hao ca mt mt lng t.u ra l 1 tp hp cc s nguyn phi c m ha bit-by-bit.Cc tham s c th c thay i t cht lng cui cng l bc lng t ha:cc bc quan trng hn l bc nn v s mt mt thng tin lng t.Vi 1 bc lng t bng 1,khng c qu trnh lng t no c thc hin(n c gi l nn khng mt mt)

3.5-Siu d liu(Metadata)i vi JPEG truyn thng, b sung cc siu d liu: lu tr cc thng tin v bc nh( kch c, su mu, phn gii, ngy to bc nh)3.6- Motion JPEG 2000 Motion JPEG quy nh vic s dng nh dng JPEG 2000 cho cc trnh t tnh thi gian ca hnh nh (t ng), c th kt hp vi m thanh, v to ra cch trnh by tng th. Tn file m rng cho cc tp video Motion JPEG 2000 l .mj2 .mjp2 Motion JPEG 2000 (thng c bit n nh MJ2 hoc MJP2) cng ang c xem xt nh l mt nh dng lu tr k thut s ca Library of Congress. N l mt tiu chun quc t m v cp nht nhng thun li cho MJPEG (hoc MJ), c da trn nhng thnh tu ca nh dng JPEG. Khng ging nh cc nh dng video ph bin, chng hn nh MPEG-4 Part 2, WMV, v H.264 th MJ2 khng s dng cc khung ni suy (inter-frame). Thay vo , mi frame l mt thc th c lp c m ha bi mt bin th hoc mt d liu hay khng gim cht lng ca JPEG 2000. N l 1 cu trc vt l khng ph thuc vo time ordering,nhng n s dung nhng profile ring bit b sung d liu. i vi m thanh, n h tr LPCM m ha, cng nh bin th khc ca MPEG-4 , nh l d liu th "hoc b sung d liu".3.7-JPEG2000 SecurityJPSECVn an ninh,bn quyn trong sao chp,truyn thng nh c x l trong JPSEC:Mt m,ngun chng thc,ton vn d liu,iu kin truy cp,bo v quyn s hu3.8-JPEG2000 Wireless-JPWLCi tin JPEG2000 cho ph hp vi cc ng dng a phng tin khng dy.3.9-JPXMLHnh nh c nhng vo XML s dng ngn ng nh du (Geography Markup Language-GML)3.10-JP3Dy l phn m rng cho hnh nh khng gian 3 chiu(th tch hnh nh)4. JPEGSearchNgy nay, nhiu nh dng siu d liu khc nhau tn ti m t hnh nh nhng vn cn nhiu vn trong kh nng tng tc.Trong bi cnh ,trng tm chnh ca JPEGSearch l cung cp mt kh nng tng tc tt hn trong tm kim hnh nh. Phin bn hin ti ca d n JPSearch c chia thnh 5 phn chnh.Phn 1 c c hon thnh: N m t cu trc tng th ca JPSearch, mt tp hp ln cc trng hp v phc tho mt kho phc hi hnh nh v cc thnh phn ca n.Phn 2: ng k, nhn dng, v qun l cc siu d liu lc (Registration, Identification, and Management of Metadata Schema): c gng vt qua nhng rc ri trong m hnh siu d liu.Phn 3:nh dng Truy vn JPSearch(JPSearch Query Format): cung cp mt giao thc thng bo chun khi phc hnh nh.Phn 4: Tp tin nh dng cho cc siu d liu nhng vo d liu hnh nh (JPEG v JPEG 2000).Phn 5: nh dng trao i d liu gia Kho Hnh nh(Data Interchange Format between Image Repositories).

5. JPEGXRL 1 nh dng hnh nh cung cp 1 s ci tin so vi JPEG1.Kh nng nn tt hn: JPEG XR nh dng tp tin h tr t l nn cao hn so vi JPEG m ha mt hnh nh vi cht lng tng ng.2.Nn khng mt mt3.H tr cu trc lt(Tile structure support).4.Cht lng mu tt hn v h tr High Dynamic Range (HDR) imaging5.H tr bn trong sut(Transparency map support)6.Gim bt vng nn nh(Compressed-domain image modification)7.H tr siu d liu(Metadata support) IV. TH NGHIM NG DNG C TH:1. Th nghim nn nh vi phn mm Advanced JPEG Compressor

nh gc ( dung lng19KB)

nh nn t l 1:10(13Kb)(nh hu nh khng khc nh gc)

nh nn t l 1:30(4.84Kb)(Cht lng nh hi km so vi nh gc)

nh nn t l 1:50(2.97Kb)(Cht lng nh sai khc ng k so vi nh gc)

nh nn t l 1:80(1.86Kb)(Lng thng tin mt mt kh ln)

nh nn t l 1:150(0.99Kb)(Cht lng nh v cng xu)

nh nn t l 1:200(0.84Kb)(Gn nh khng th xc nh ch th bc nh)

So snh vi cc nh dng nh khcs dng phn mm ReaCompressor

nh JPG(6.1Kb)

nh GIF(36Kb)

nh PNG(81Kb)

nh TIF(5Kb)

1. KT LUN:Cng ngh nn nh JPEG l mt phng php nn nh v cng hiu qu. Trong s pht trin ca cng ngh thng tin v Internet th JPEG l mt cng c rt hu hiu trong vic truyn thng tin v lu tr thng tin. Trong qu trnh pht trin, JPEG ngy cng c ci tin khc phc nhng nhc im ca mnh tr thnh nh dng nh ph bin nht trn th gii. Tuy nhin, v JPEG l chun khng bo ton bi thng tin v nh s b thay i khi n b m ha nhiu ln. V vy m cc chuyn gia trn th gii bt u nghin cu cc nh dng nh tha k nhng u im ca JPEG m hn ch c s mt mt thng tin. C th k n nh dng Webp do google pht trin. V chng ta cng ch i nhiu nh dng nh khc hiu qu hn ra i trong tng lai gn

1. TI LIU THAM KHO

1. Gio trnh X l nh Nguyn Th Hong Lan1. Wikipedia , jpeg.org, .v.v.1. S dng cc phn mm Advanced JPEG Compressor, ReaCompressor.

1. THE END!!!

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