Lossy Compression: Nws Yog Dab Tsi thiab Yuav Siv Li Cas

by kim Kho tshiab: Lub rau hli ntuj 28, 2022

Lossy compression yog ib txoj hauv kev siv los txo cov ntaub ntawv ntau thiab tsawg yam tsis muaj kev cuam tshuam txog kev ncaj ncees ntawm cov ntaub ntawv qub.

Nws tso cai rau koj mus nqa cov ntaub ntawv loj uas muaj ntau cov ntaub ntawv thiab txo lawv qhov loj me los ntawm tshem tawm qee cov ntaub ntawv tab sis tsis cuam tshuam qhov zoo tag nrho. Qhov no tuaj yeem tau txais txiaj ntsig tshwj xeeb thaum cuam tshuam nrog cov video loj lossis cov duab cov ntaub ntawv.

Cov seem ntawm tsab xov xwm no yuav piav qhia txog cov hauv paus ntsiab lus ntawm kev poob compression thiab yuav ua li cas thov thiab siv tau zoo:

Lub ntsiab lus ntawm Lossy Compression

Lossy compression yog ib hom ntaub ntawv compression txheej txheem uas siv txoj kev los txo qhov loj ntawm cov ntaub ntawv los yog cov ntaub ntawv kwj yam tsis tau poob loj npaum li cas ntawm nws cov ntaub ntawv cov ntsiab lus. Hom compression no ua rau cov ntaub ntawv me dua li lawv cov qauv qub thaum ua kom ntseeg tau tias qhov zoo, meej, thiab kev ncaj ncees ntawm cov ntaub ntawv khaws cia. Nws ua haujlwm los ntawm kev xaiv tshem tawm ib feem ntawm cov ntaub ntawv xov xwm (xws li suab lossis duab) uas tseem tsis pom zoo rau tib neeg lub siab. Lossy compression tau nyob ib ncig ntawm ntau xyoo thiab nws txoj kev siv tau nrov zuj zus vim kev nce qib hauv kev siv tshuab.

Hom compression no muaj txiaj ntsig zoo nyob rau hauv cov xwm txheej uas bandwidth lossis qhov chaw cia yog txwv, ua rau nws muaj txiaj ntsig tshwj xeeb hauv:

• Streaming apps xws li video-on-demand (VoD),
• satellite tshaj tawm,
• Cov duab kho mob,
• Digital audio formats.

Cov txheej txheem no kuj tseem siv dav hauv daim ntawv thov audio thiab duab editor kom muaj txiaj ntsig zoo nrog cov ntaub ntawv qis dua thaum txuag cov ntaub ntawv kho qhov project. Lossy compression tuaj yeem siv rau lwm hom ntaub ntawv xws li cov ntawv nyeem ntev npaum li tsis muaj cov ntsiab lus tseem ceeb ploj thaum lub sijhawm ua haujlwm.

Hauv kev sib piv rau lossy compression, yog muaj lossless compression uas sim txo qis qhov cuam tshuam ntawm kev tawm tswv yim thiab cov ntaub ntawv tso tawm cov kwj deg yam tsis tau txo qhov kev nkag siab meej los ntawm kev siv cov ntaub ntawv rov qab los ntawm cov khoom siv hauv nws tus kheej es tsis txhob rho tawm cov ntaub ntawv los ntawm nws.

Cov txiaj ntsig ntawm Lossy Compression

Lossy compression yog ib txoj hauv kev zoo ntawm kev txo cov ntaub ntawv loj thaum tseem tswj hwm tag nrho cov duab zoo. Tsis zoo li ntau tsoos Lossless cov ntaub ntawv compression txheej txheem, uas xaiv thiab muab pov tseg redundancies hauv cov ntaub ntawv kom txo qhov loj me thiab nce kev sib kis ceev, lossy compression ua haujlwm los ntawm kev xaiv pov tseg cov ntaub ntawv tsis tseem ceeb thiab rov ua dua hauv cov ntaub ntawv. Hom compression no siv algorithms los tshuaj xyuas cov ntaub ntawv hauv cov ntaub ntawv digital thiab tshem tawm qhov tsis tsim nyog yam tsis muaj kev cuam tshuam rau tag nrho cov txiaj ntsig zoo lossis qhov kawg.

Thaum siv kom raug, lossy compression tuaj yeem muab ntau yam txiaj ntsig, xws li:

• Txo qhov yuav tsum tau khaws cia: Los ntawm kev tshem tawm cov ntsiab lus tsis cuam tshuam los ntawm cov ntaub ntawv digital, qhov tshwm sim ntawm cov duab loj tuaj yeem ua rau me dua li nws qhov qub qub, muab kev txuag nyiaj ntau dua rau cov webmasters.
• Txhim kho kev sib kis ceev: Lossy compression algorithms siv cov ntaub ntawv tsawg dua los ntawm kev tshem tawm cov ntaub ntawv tsis tsim nyog los ntawm cov duab uas tsis pom rau tib neeg lub qhov muag. Qhov no txhais tau hais tias cov ntaub ntawv xa mus thoob plaws hauv tes hauj lwm tuaj yeem ua tau sai dua li lawv cov qauv qub yam tsis muaj kev txi zoo.
• Txhim khu kev pom: Nrog rau qhov txo qis ntawm cov ntaub ntawv loj tuaj los txhim kho kev pom kev paub thaum tshawb hauv online lossis saib cov duab ntawm cov khoom siv txawb. Lossy compressed dluab coj mus txog tsawg lub cim xeeb ntawm cov cuab yeej hard drives uas pab nrog cov duab rendering kev ua tau zoo thaum thauj cov duab lossis saib cov nplooj ntawv web.

Hom Lossy Compression

Lossy compression yog cov txheej txheem compression cov ntaub ntawv uas txo qhov loj ntawm cov ntaub ntawv los ntawm kev pov tseg qhov chaw ntawm nws cov ntaub ntawv uas pom tias tsis tsim nyog. Nws pab tau optimize cov ntaub ntawv loj thiab tuaj yeem pab txuag tau qhov chaw cia. Hom kev compression no tuaj yeem siv rau ntau yam kev siv xws li cov duab, suab, thiab cov ntaub ntawv video.

Hauv kab lus no, peb yuav tham txog qhov plaub hom lossy compression, lawv qhov zoo, thiab qhov tsis zoo:

JPEG

JPEG (Joint Photographic Experts Group) yog tus qauv rau lossy compression ntawm cov duab digital. JPEG txhawb 8-ntsis, greyscale dluab thiab 24-ntsis xim duab. JPG ua haujlwm zoo tshaj plaws ntawm cov duab, tshwj xeeb tshaj yog cov uas muaj ntau yam nthuav dav.

Thaum tsim JPG, cov duab tau muab faib ua cov blocks me me hu ua 'macroblocks'. Cov qauv lej txo cov xim muaj xim lossis cov suab nrov hauv txhua qhov thaiv thiab tshem tawm qhov tsis zoo uas yog qhov muag rau peb, tab sis tsis yog rau cov khoos phis tawj. Nws sau tag nrho cov kev hloov pauv hauv cov blocks no kom nws rov qab mus rau lawv thiab sau lawv cov qub xeev txhawm rau txo lawv qhov loj me. Thaum ib daim duab tau txais kev cawmdim li JPG, nws yuav tshwm sim me ntsis nyob ntawm seb compression tau siv npaum li cas los txo nws qhov loj. Cov duab zoo txo ​​qis thaum siv compression ntau dua thiab cov khoom qub yuav pib tshwm - nrog rau lub suab nrov thiab pixelation. Ntawm kev txuag cov duab raws li JPG koj tuaj yeem xaiv qhov tseeb npaum li cas yuav tsum tau txi rau qhov txo qis ntawm cov ntaub ntawv - feem ntau hu ua "zoo". Qhov kev teeb tsa no cuam tshuam rau tus nqi ntawm compression poob siv rau ntawm koj cov ntaub ntawv.

MPEG

MPEG (Txiv Cov Kws Tshaj Lij Pab Pawg) yog hom ntawm compression poob uas yog siv feem ntau rau cov ntaub ntawv audio thiab video. Nws tau tsim los ua tus qauv rau compressing cov ntaub ntawv multimedia thiab tau dhau los ua neeg nyiam ntau xyoo. Lub tswv yim tseem ceeb tom qab MPEG compression yog txo qhov loj ntawm cov ntaub ntawv yam tsis muaj kev cuam tshuam qhov zoo - qhov no yog ua los ntawm kev muab pov tseg qee yam ntawm cov ntaub ntawv uas tsis yog qhov tseem ceeb rau cov neeg saib.

MPEG compression ua haujlwm los ntawm kev tshuaj xyuas cov yeeb yaj kiab, rhuav tshem nws mus rau hauv chunks, thiab txiav txim siab txog qhov twg tuaj yeem muab pov tseg kom nyab xeeb, thaum tseem tswj hwm qib kev ua tau zoo. MPEG tsom rau cov khoom txav nyob rau hauv cov ntaub ntawv video; Cov khoom uas tsis txav mus rau hauv ib qho xwm txheej yog qhov yooj yim dua rau compress dua li cov khoom uas txav mus los yog muaj kev hloov pauv sai ntawm cov xim lossis lub teeb ci. Siv cov algorithms siab heev, MPEG tuaj yeem tsim cov qauv ua tau zoo ntawm txhua tus ncej hauv cov ntaub ntawv thiab tom qab ntawd siv cov thav ntawv los sawv cev ntau dua ntawm qhov chaw.

Tus nqi ntawm qhov zoo poob vim MPEG compression nyob ntawm ob qho tib si xaiv algorithm thiab chaw siv. Kev lag luam tawm ntawm no yog qhov loj thiab zoo; cov chaw siab dua yuav ua rau cov txiaj ntsig zoo dua tab sis ntawm tus nqi ntau dua ntawm qhov chaw; conversely, qhov chaw qis dua yuav tsim cov ntaub ntawv me me nrog cov txiaj ntsig tsis zoo, tshwj xeeb tshaj yog thaum nws los txog Cov yeeb yaj kiab loj xws li cov yeeb yaj kiab ntev ntev lossis cov yeeb yaj kiab siab haum rau HDTVs.

MP3

MP3, los yog Tsiv Duab Cov Kws Paub Pab Pawg Suab Txheej 3, yog ib tug compressed suab hom uas siv ib tug ntau yam ntawm tej algorithms los txo tus thawj loj ntawm cov ntaub ntawv audio. Nws yog suav hais tias yog ib qho ntawm cov hom nrov tshaj plaws vim nws qhov ua tau zoo hauv compressing cov suab nkauj rau hauv qhov me me dua li lwm yam poob hom ntawv. MP3 siv ib daim ntawv "lossy" compression uas tshem tawm qee qhov ntawm cov ntaub ntawv kaw cia thiab ua kom yooj yim dua rau cov khoom siv xws li cov suab paj nruag portable khaws cia thiab tshaj tawm cov suab paj nruag ntau.

MP3 tuaj yeem nthuav tawm txhua hom kev sib xyaw digital xws li los ntawm mono, duplicate mono, tso suab, dual channel thiab sib koom ua ke tso suab. Tus qauv MP3 txhawb 8-320Kbps ntsis-tus nqi (kilobits ib ob) compresses lub suab ntaub ntawv rau hauv 8kbps uas yog haum rau streaming lub hom phiaj. Nws muaj kev nce qib ntawm lub suab zoo mus txog 320Kbps nrog lub suab siab dua thiab siab dua bitrate muab ntau lub suab zoo dua qub ntawm cov ntaub ntawv loj dua uas ua rau lub sijhawm rub tawm qeeb. Thaum siv txoj kev compression no, nws yuav raug rau cov neeg siv kom ua tiav qhov nruab nrab 75% txo cov ntaub ntawv loj tsis muaj kev poob rau hauv kev mloog kev lom zem lossis kev pom meej vim nws cov coding system uas muaj txiaj ntsig hloov pauv cov ntaub ntawv ntau dua thaum tswj hwm lub suab zoo.

Yuav Siv Lossy Compression li cas

Lossy compression yog ib hom ntaub ntawv compression uas txo cov ntaub ntawv los ntawm tshem tawm qee qhov ntawm nws cov ntaub ntawv. Qhov no yuav ua rau cov ntaub ntawv me me thiab yog li ntawd, kev rub tawm nrawm dua. Lossy compression yog ib qho cuab yeej zoo siv thaum koj xav tau nrawm nrawm cov ntaub ntawv loj.

Hauv kab lus no, peb yuav tham txog:

• Yuav ua li cas siv compression poob
• Cov txiaj ntsig zoo li cas
• yuav ua li cas optimize cov ntaub ntawv koj compress

Cov Lus Qhia Txuas Ntxiv-Ib-Ntxiv

Kev siv lossy compression feem ntau xav tau cov kauj ruam hauv qab no:

1. Xaiv hom ntaub ntawv lossis cov ntaub ntawv koj xav kom compress - Nyob ntawm qhov xav tau cov ntaub ntawv loj thiab qib zoo, hom compressed hom yuav txawv. Hom hom muaj xws li JPEG, MPEG, thiab MP3.
2. Xaiv cov cuab yeej compression - Cov cuab yeej compression sib txawv siv cov algorithms sib txawv los tsim ntau theem ntawm cov ntaub ntawv compression. Qee cov cuab yeej nrov yog WinZip, zipX, 7-Zip thiab WinRAR rau cov neeg siv Windows; Khoom X rau cov neeg siv Mac; thiab iZarc rau cov neeg siv ntau lub platform.
3. Kho qhov chaw compression - Txhawm rau tsim kom muaj txiaj ntsig zoo dua, hloov kho xws li hloov qib ntawm compression, duab daws teeb meem lossis lwm qhov chaw teeb tsa hauv ib hom compressed ua ntej compressing cov ntaub ntawv. Kuj saib mus rau hauv cov chaw uas optimize dluab rau web saib yog muaj.
4. Compress cov ntaub ntawv lossis cov ntaub ntawv - Pib cov txheej txheem compressions los ntawm txhaj pib lossis "OK" hauv koj daim ntawv thov thaum ua tiav nrog koj cov kev hloov kho. Nyob ntawm seb qhov loj ntawm cov ntaub ntawv raug compressed, nws yuav siv sij hawm ob peb feeb los ua kom tiav cov txheej txheem no nyob ntawm qhov ceev ntawm processor thiab software thov siv.
5. Uncompress cov ntaub ntawv lossis cov ntaub ntawv - Cov txheej txheem rho tawm yuav tso cai rau koj nkag mus rau koj cov ntaub ntawv tshiab shrunken ib zaug ua tiav kom koj tuaj yeem pib siv tam sim ntawd txawm li cas los xij zoo tshaj plaws rau koj qhov project ntawm tes. Siv cov ntaub ntawv xav tau los ntawm compressed folders hom feem ntau txawv ntawm .zip .rar .7z .tar .iso thiab lwm yam.. Unzip extraction tsuas yog rho tawm cov compressed yam ntawm daim ntaub ntawv xws li WinZip, 7Zip, IZarc thiab lwm yam.. tso cai rau tus kheej tswj hwm cov khoom uas koj xav tau nkag mus rau lub sijhawm twg los tau thaum ua kom lwm tus nyob hauv cov ntaub ntawv tiv thaiv nruj nruj raws li koj nyiam!

Qhov zoo tshaj plaws Practices

Thaum siv compression poob, nws yog ib qho tseem ceeb uas yuav tsum tau siv hom ntawv zoo rau daim ntawv thov raug. Piv txwv li, yog tias koj xav tau muab cov ntaub ntawv nthuav qhia rau lwm tus neeg, ces koj yuav tsum siv a Lossy duab format txij li cov kev nthuav qhia feem ntau tshwm sim ntawm qhov kev daws teeb meem qis dua thiab me me.

Muaj ntau ntau txoj hauv kev los ua kom muaj txiaj ntsig zoo ntawm kev poob compression. Nov yog qee qhov kev coj ua zoo tshaj plaws:

• Xaiv ib hom compression tsim nyog raws li koj cov ntaub ntawv siv (jpeg rau cov duab, mp3 rau suab, thiab lwm yam).
• Teem ib qib zoo tsim nyog nyob ntawm seb koj xav muab cov ntaub ntawv pov tseg ntau npaum li cas.
• Kho qhov ntsuas raws li koj xav tau; txheeb xyuas qhov sib pauv ntawm cov ntaub ntawv loj thiab zoo.
• Nco ntsoov tias siv lossy compression ntau zaug tuaj yeem ua rau pom cov khoom cuav hauv koj cov ntaub ntawv tawm thiab degrade lawv qhov zoo ntau dua li ib qho dhau ntawm compression feem ntau yuav.
• Nco ntsoov tias cov metadata cuam tshuam nrog cov ntaub ntawv compressed raug khaws cia kom zoo kom txhua cov ntaub ntawv tseem ceeb tseem muaj thaum faib lossis nthuav tawm cov ntsiab lus ntawm cov ntaub ntawv.

xaus

Thaum xaus, compression poob yog ib txoj hauv kev zoo los txo cov ntaub ntawv qhov ntau thiab tsawg thiab txo lub sijhawm thauj khoom ntawm cov vev xaib thaum tseem khaws ib qib siab zoo. Nws tso cai rau koj txo cov ntaub ntawv loj ntawm cov duab lossis cov ntaub ntawv audio yam tsis muaj kev cuam tshuam loj ntawm cov ntaub ntawv zoo. Nws tseem ceeb heev uas yuav tsum nco ntsoov, txawm li cas los xij, qhov ntawd compression poob tseem yuav cuam tshuam qhov zoo ntawm cov ntaub ntawv thiab yuav tsum tau siv nrog kev saib xyuas.

Summary of Lossy Compression

Lossy compression yog ib hom ntaub ntawv compression uas txo cov ntaub ntawv loj los ntawm kev tshem tawm ib co ntawm cov ntaub ntawv uas muaj nyob rau hauv thawj cov ntaub ntawv. Cov txheej txheem no feem ntau ua rau cov ntaub ntawv me dua li cov ntaub ntawv qub thiab tau compressed siv algorithms xws li JPEG, MP3 thiab H.264 npe ob peb. Lossy compression cov tswv yim zoo li kev lag luam tawm qee qhov zoo rau qhov loj me tab sis optimized algorithms tuaj yeem tsim cov ntaub ntawv nrog qhov sib txawv me ntsis ntawm qhov tsis sib xws.

Thaum ua ntawv thov lossy compression, nws yog ib qho tseem ceeb uas yuav tau xav txog ntau npaum li cas qhov zoo yuav ua tau rau lub hom phiaj txo cov ntaub ntawv loj. Qee qhov lossy compressions tuaj yeem txo cov ntaub ntawv loj heev thaum muab cov kev poob qis qis thaum lwm tus tuaj yeem tsim cov ntaub ntawv me me tab sis nrog qhov tsis txaus ntseeg lossis cov khoom cuav. Feem ntau, yog tias xav tau kev txo qhov loj dua, ces qhov kev poob zoo tuaj yeem xav tau thiab rov ua dua.

Zuag qhia tag nrho, lossy compression muab txoj hauv kev zoo los txo cov ntaub ntawv ntau thiab tsawg yam tsis muaj kev cuam tshuam ntau dhau kev ua haujlwm piv rau cov ntawv tsis txaus siab hauv ntau lub sijhawm; Txawm li cas los xij, cov teeb meem no yuav tsum raug ntsuas raws li qhov xwm txheej ua ntej txiav txim siab seb nws puas tsim nyog los daws qhov teeb meem.

Qhov zoo ntawm Kev Siv Lossy Compression

Lossy compression muab ntau qhov zoo rau cov ntaub ntawv xov xwm digital. Qhov zoo tshaj plaws kom pom tseeb yog tias lossy compression muaj ntau dua txo cov ntaub ntawv loj dua li qub Lossless compression algorithms. Qhov no pab khaws cia thiab kev siv bandwidth kom tsawg kawg nkaus thaum hloov cov ntaub ntawv xov xwm loj hauv internet, lossis rau compressing rau hauv zos cia.

Ntxiv rau qhov muab cov ntaub ntawv zoo dua txo qis dua li cov txheej txheem lossless ib txwm, kev siv lossy compression kuj ua rau nws tuaj yeem txo cov ntaub ntawv ntau thiab tsawg dua thaum tseem tswj hwm qib kev ua tau zoo (nyob ntawm seb hom xov xwm raug compressed). Tsis tas li ntawd, siv lossy algorithms tso cai rau cov neeg siv hauv zos kho cov duab thiab suab zoo raws li xav tau yam tsis tas yuav rov encode tag nrho cov ntaub ntawv - qhov no ua rau txuag cov ntaub ntawv yooj yim dua thiab sai dua vim tias tsuas yog ib feem ntawm cov ntaub ntawv xov xwm yuav tsum tau hloov kho.

Thaum kawg, siv lossy algorithms kuj tuaj yeem muab kev ruaj ntseg ntxiv rau qee kis; Txij li thaum lub suab qis qis feem ntau tsis tshua muaj qhov sib txawv thiab nyuaj dua los txhais qhov sib npaug piv nrog cov qib bitrate siab dua, nws tuaj yeem muab cov txheej txheem ntxiv ntawm kev ruaj ntseg yog cov ntaub ntawv loj xav tau kev tiv thaiv los ntawm kev mloog tsis tau tso cai lossis saib. Lossy compression muaj ntau yam txiaj ntsig ua kom nws nrov ntawm cov neeg siv xov xwm digital uas xav tau cov ntaub ntawv me me nrog kev siv zog tsawg.

Nyob zoo, Kuv yog Kim, niam thiab ib tus neeg nyiam nres nrog keeb kwm yav dhau los hauv kev tshaj tawm thiab kev txhim kho lub vev xaib. Kuv muaj kev mob siab rau kev kos duab thiab kev ua yeeb yam, thiab tam sim no kuv tab tom dhia taub hau ua ntej mus rau hauv lub ntiaj teb nres. Nrog rau kuv qhov blog, Kuv tabtom qhia kuv cov kev kawm nrog koj.