Iyini i-algorithm yokucindezela i-JPEG?

Iyini ⁢JPEG compression algorithm?

I-algorithm yokuminyanisa ye-JPEG (Joint Photographic Experts Group) iyindinganiso esetshenziswa kabanzi ekuminyanisweni kwezithombe zedijithali, ikakhulukazi ekuthwebuleni nasekuthumeleni izithombe nge-inthanethi. Le algorithm ikuvumela ukuthi unciphise usayizi wamafayela wesithombe ngaphandle kokulahlekelwa inani elibalulekile lekhwalithi ebonakalayo. Kuyaziwa ngokusebenza kwayo nokuthandwa kwayo ezinhlelweni ezihlukahlukene.

1. Isingeniso ku-JPEG compression algorithm

I-algorithm yokucindezela ye-JPEG iyindlela esetshenziselwa ⁢ukunciphisa usayizi wamafayela esithombe, ngaphandle kokuthikame kakhulu ikhwalithi yawo yokubonwa.⁢ Yathuthukiswa ngo-1992⁤ yi-Joint Photographic Expert Group (JPEG)⁤ futhi isibe ngeyodwa edume kakhulu. izindlela zokucindezela izithombe zedijithali.

Ukucindezelwa kwe-JPEG kuthathwa njengokucindezelwa "okulahlekile", okusho ukuthi Kukhona ukulahlekelwa kolwazi phakathi nenqubo yokucindezela. Kodwa-ke, lokhu kulahlekelwa akubonakali emehlweni abantu ezimweni eziningi, njengoba idatha eningi engabonakali ngeso lenyama iyaqedwa. Lokhu kwenza ukucindezelwa kwe-JPEG kulungele ukuboniswa kwesithombe kumadivayisi anjengamakhamera edijithali, omakhalekhukhwini kanye amawebhusayithi.

I-algorithm yokucindezela ye-JPEG isebenzisa inhlanganisela yamasu okucindezela afana ne-discrete cosine transform (DCT) kanye ne-quantization. I-DCT ihlukanisa isithombe sibe amabhlogo angamaphikseli angu-8x8⁢ futhi iguqule ibhulokhi ngayinye ibe uchungechunge lwama-coefficients amelela amafrikhwensi esithombe. I-quantization ibe isisetshenziswa, lapho ukunemba kwalawa ma-coefficients kwehliswa ukuze kuncishiswe inani ledatha edingekayo ukumela isithombe. Le nqubo Ukuguqulwa kanye nokulinganisa⁢ kwenziwa ngokuphindaphindiwe kuze kube yilapho ukucindezela okufunayo kufinyelelwa.

2. Izimiso eziyisisekelo ze-algorithm yokucindezela ye-JPEG

I-algorithm yokucindezela ye-JPEG iyindlela esetshenziswa kakhulu yokunciphisa usayizi wamafayela esithombe ngaphandle kokulahlekelwa ikhwalithi yokubukwayo kakhulu. Le-algorithm isuselwe ekuqedweni kokuphinda kwenziwe kabusha kanye nokucindezelwa okukhethiwe kwedatha yesithombe. Inzuzo eyinhloko ye-algorithm ye-JPEG yikhono layo lokucindezela izithombe ngokunciphisa okuphawulekayo kosayizi wefayela, okuvumela ukugcinwa okulula nokudluliswa kwezithombe zedijithali.

Inqubo yokucindezela i-JPEG isekelwe ezigabeni ezimbili eziyinhloko: ukuguqulwa kusuka kusizinda sendawo kuya kusizinda semvamisa kusetshenziswa i-discrete cosine transform (DCT), kanye ne-quantization ye-DCT coefficients. Lolu shintsho luvumela idatha yesithombe ukuthi imelelwe⁢ ngokuya ngokuqukethwe kwaso okuyimvamisa, okusiza ukuminyanisa izingxenye zefrikhwensi ephezulu⁢ kanye nokususwa kwemininingwane engabonakali ngeso lomuntu.

Esinye isici esibalulekile se-algorithm yokuminyanisa ye-JPEG ukusetshenziswa kombhalo wekhodi we-Huffman ukumela idatha yesithombe kahle kakhulu. Ukubhala ngekhodi kwe-Huffman kunikeza amakhodi amafushane kumafrikhwensi okwenzeka aphezulu kakhulu namakhodi amade kumafrikhwensi ezenzeko aphansi kakhulu, kuqhubeke kwehlisa usayizi wekhodi. ifayela elicindezelwe ⁤ngaphandle kokulahlekelwa okubonakalayo kwekhwalithi. Ngaphezu kwalokho, i-algorithm ye-JPEG iphinde isekele amazinga okucindezela ahlukene, okukuvumela ukuthi ulungise ikhwalithi yesithombe ngokuvumelana nezidingo ezithile.

3. Inqubo yokucindezelwa kwe-algorithm ye-JPEG

El I-algorithm yokucindezela ye-JPEG kuyindlela esetshenziswa kabanzi yokunciphisa usayizi wamafayela esithombe ngaphandle kokuthikameze kakhulu ikhwalithi yawo yokubuka. Le nqubo isekelwe esimisweni sokucindezelwa kokulahlekelwa, okusho ukuthi imininingwane ethile isusiwe esithombeni ezingabonakali ngeso lomuntu. I-algorithm ye⁤ isebenza ngokuhlukanisa isithombe sibe amabhulokhi wamaphikseli bese isebenzisa uchungechunge lwezinguquko zezibalo ukuze kuncishiswe ukuphindaphindeka kolwazi.

Esinye sezinyathelo ezibalulekile yi- ukuguqulwa kwesizinda se-frequency. Kulesi sinyathelo, isithombe siguqulwa sisuka esizindeni sendawo⁤ siye kusizinda semvamisa kusetshenziswa i-discrete cosine transform (DCT). I-DCT ibolisa ⁢isithombe sibe uchungechunge lwezingxenye ezihlukene zefrikhwensi⁢, ngamafrikhwensi aphansi amele imininingwane ebaluleke kakhulu yesithombe namafrikhwensi aphezulu amele imininingwane ecolekile.

Esinye isinyathelo esibalulekile senqubo yokucindezelwa kwe-JPEG yi- quantization. Kulesi sinyathelo, ⁤ama-coefficients wefrequency atholwe ku-DCT ahlukaniswa ngochungechunge lwamanani achazwe ngaphambilini okulinganisa. Lokhu kuphumela ⁢ku⁢ a ukulahlekelwa ukunemba kuma-coefficients wefrequency, okuvumela ukuncishiswa okwengeziwe kosayizi wefayela. Ukulinganisa kwenani kwenziwa ngendlela yokuthi amaphutha ethulwe ⁤angabonakali emehlweni omuntu, ngaleyo ndlela aqinisekise ikhwalithi yokubukwa eyamukelekayo yesithombe esicindezelwe.

4. Ukuhlaziywa kwekhwalithi yesithombe kusetshenziswa i-algorithm ye-JPEG

I-algorithm yokucindezela ye-JPEG ingenye esetshenziswa kakhulu ukunciphisa usayizi wamafayela. amafayela esithombe ngaphandle kokulahlekelwa ikhwalithi eningi. Le algorithm isebenzisa inqubo yokucindezela elahlekile, okusho ukuthi imininingwane ethile iyasuswa esithombeni ukuze kuncishiswe usayizi waso. Kodwa-ke, inani lemininingwane ekhishwayo liyalawulwa futhi inhloso ukulondoloza ikhwalithi ebonakalayo yesithombe.

Ikhwalithi yesithombe ihlaziywa kusetshenziswa i-algorithm ye-JPEG ngokuhlola i- ubudlelwano phakathi kosayizi wefayela ocindezelwe kanye nekhwalithi yesithombe esibonwayo. Ukwenza lokhu, i-JPEG isebenzisa imethrikhi ebizwa nge-PSNR (Peak Signal-to-Noise Ratio) ekala umehluko phakathi kwesithombe sokuqala nesithombe esicindezelwe. Inani eliphakeme le-PSNR libonisa ikhwalithi yesithombe engcono, njengoba kusho ukuthi umehluko phakathi kwakho kokubili mincane.

Esinye isici esibalulekile yi- isilinganiso sokucindezela. Lesi silinganiso sibalwa ngokuhlukanisa usayizi wefayela langempela ngosayizi wefayela elicindezelwe. Ukuphakama kwalesi silinganiso, ukucindezelwa okukhulu kanye nosayizi wefayela omncane, kodwa futhi kukhulu ukulahlekelwa kwekhwalithi. Ngakho-ke, kubalulekile ukuthola ibhalansi phakathi kosayizi wefayela kanye nekhwalithi yesithombe oyifunayo.

5. Izinzuzo kanye nokubi kwe-algorithm yokucindezela ye-JPEG

I-algorithm yokucindezela ye-JPEG iyindlela esetshenziswa kabanzi yokunciphisa usayizi wefayela wezithombe ngaphandle kokulahlekelwa okuphawulekayo kwekhwalithi. Lokhu kufezwa ngokususa imininingwane engadingekile nokusebenzisa indlela yokucindezela esekelwe ekucutshungulweni kwe-discrete cosine transform (DCT).

Enye yezinzuzo eziyinhloko ze-algorithm yokucindezela ye-JPEG yikhono layo lokunciphisa usayizi wefayela kuze kufike ku-95% uma kuqhathaniswa nefayela lokuqala elingacindezelwanga. Lokhu kuwusizo ikakhulukazi ezimweni lapho i- isikhala sediski ⁣⁣⁣ sikhawulelwe noma lapho isivinini sokulayisha isithombe sibalulekile, njengakumongo wewebhu. Ukwengeza, ukucindezela kwe-JPEG kuvumela ukuboniswa kancane kancane kwezithombe, okusho ukuthi izithombe zingalayishwa ngokushesha ngokulungiswa okuphansi bese zicwengisiswa kancane kancane zibe yikhwalithi egcwele.

Nokho, kukhona futhi izinkinga kuhlotshaniswa ne-algorithm yokucindezela ye-JPEG. Enye yezingqinamba eziyinhloko ukuthi ukucindezelwa kwe-JPEG kuyi-algorithm yokulahlekelwa, okusho ukuthi ikhwalithi yesithombe iyathinteka njengoba usayizi wefayela uncishisiwe. ⁣Lokhu kungase kuphumele ekuncipheni kobukhali bemininingwane emihle kanye nama-artifact aminyanisiwe afana nokuvinjwa kwesithombe. Ukwengeza, ukuminyanisa ⁢JPEG akuzifanele izithombe lapho kubalulekile ukulondoloza yonke imininingwane nemibala, njengasendabeni yezokwelapha. izithombe noma izithombe zochwepheshe.

Kafushane, i-algorithm yokucindezela ye-JPEG iyithuluzi eliwusizo elikuvumela ukuthi unciphise kakhulu usayizi wamafayela wesithombe ngaphandle kokulahlekelwa okuphawulekayo kwekhwalithi. Nokho, Kubalulekile ukucabangela ukulinganiselwa kwale algorithm futhi uhlole ukuthi Kungcono kakhulu inketho yecala ngalinye. Uma umgomo uwukugcina ikhwalithi ephezulu kakhulu yesithombe, ezinye izindlela zokucindezela ezingalahleki zingase zidinge ukuthi zicatshangelwe ekugcineni, ukukhetha i-algorithm efanele yokuminyanisa kuzoncika ezidingweni ezithile nasezimfuneko zephrojekthi ngayinye.

6. Izincomo zokuthuthukisa ukucindezelwa kwe-JPEG

Ukucindezelwa kwe-JPEG kuyi-algorithm esetshenziswa kabanzi ukunciphisa usayizi wezithombe ngaphandle kokuphazamisa kakhulu ikhwalithi yazo yokubuka. Ukuze uthuthukise ukucindezelwa kwe-JPEG, kubalulekile ukulandela izincomo ezithile ezizosiza ukuthola imiphumela ikhwalithi ephezulu kanye nosayizi wefayela omncane.

1. Lungisa izinga lokuminyanisa: I-algorithm ye-JPEG ikuvumela ukuthi ulungise izinga lokucindezela ukuze ulinganise ikhwalithi yokubuka nosayizi wefayela. Kubalulekile ukuthola izinga elilungile elikuvumela ukuthi unciphise usayizi wefayela ngaphandle kokubangela ukuwohloka ngokweqile kwekhwalithi yesithombe. Ngokuvamile, izinga lokucindezela phakathi kuka-50% no-80% linikeza ibhalansi enhle.

2. Gwema ukucindezela okulandelanayo: Ukwenza ukuminyaniswa okuningi okulandelanayo esithombeni esifanayo kungabangela ukulahlekelwa kwekhwalithi okunqwabelene. Kutuswa ukuthi uhlale ugcina ikhophi yefayela langempela elingacindezelwanga ⁣futhi⁢ usebenze kumakhophi ukuze ugweme ukucekelwa phansi.

3. Susa ulwazi olungafuneki: Ngaphambi kokuminyanisa isithombe, kuyatuseka ukuthi wenze izinguquko ukuze ukhiphe ulwazi olungafuneki. Lokhu kuhlanganisa ukunqampuna okufanele kwesithombe, ukususa izinto ezingadingekile, nokunciphisa ukujula kombala uma kungenzeka. Lezi zinyathelo zizosiza ukunciphisa usayizi wefayela futhi zithuthukise ukusebenza kahle kokucindezela.

7. Izinhlelo zokusebenza nokusetshenziswa kwe-algorithm yokucindezela ye-JPEG

El I-algorithm yokucindezela ye-JPEG Kuyindinganiso esetshenziswa kabanzi embonini yezithombe nedijithali. Iyakwazi ukunciphisa usayizi ngokuphawulekayo kusuka kufayela yesithombe ngaphandle kokubeka engcupheni ikhwalithi yokubukwayo kakhulu. Lokhu kufezwa ngokukhetha ngokukhetha ukwaziswa okungenasidingo kanye nemininingwane engabonakali ngeso lomuntu.

Enye yezinto eziyinhloko Izinhlelo zokusebenza ze-algorithm yokucindezela ye-JPEG Isekudlulisweni kwezithombe nge-inthanethi. Izithombe ezinkulu, ezingacindezelwanga zingathatha isikhathi eside ukulayishwa, okuholela ekuzizwiseni kabi komsebenzisi. Ngokusebenzisa i-algorithm ye-JPEG, kungenzeka ukunciphisa usayizi wezithombe, okuvumela ukudluliswa okushesha nokusebenza kahle.

Okunye ukusetshenziswa okuvamile kwe-algorithm yokucindezela ye-JPEG isendaweni yokugcina izithombe kumadivayisi anamandla alinganiselwe, njengamakhamera edijithali noma omakhalekhukhwini. Lawa madivayisi ngokuvamile anenani elilinganiselwe lesikhala sokulondoloza,⁣ ngakho ikhono lokuminyanisa izithombe ngaphandle kokulahlekelwa yikhwalithi eningi libalulekile. I-algorithm ye-JPEG ivumela abasebenzisi ukuthi bagcine izithombe eziningi kumadivayisi abo ngaphandle kokuthatha isikhala esiningi.