Lub Tshuab Ua Xim rau ntawm LED Televisions
Cov TV LED (Light Emitting Diode) tau dhau los ua tus qauv kub rau cov khoom siv tso saib hauv tsev thiab cov chaw pej xeem vim tias lawv muab cov duab ci, nyias, txuag hluav taws xob, thiab pheej yig. Txawm hais tias feem ntau hu ua "LED TVs," feem ntau ntawm cov khoom siv no yog LCD TVs uas siv LED backlights. Qhov zoo ntawm cov duab uas peb pom - tshwj xeeb tshaj yog qhov tseeb ntawm xim, qib sib piv, thiab gradations - tsis yog txiav txim siab los ntawm lub vaj huam sib luag tso saib xwb, tab sis kuj los ntawm lub kaw lus ua haujlwm xim ua haujlwm tom qab qhov xwm txheej. Tsab xov xwm no tham txog yuav ua li cas xim ntawm LED TV raug ua tiav los ntawm qhov chaw teeb liab kom thaum kawg tshwm sim ua duab nplua nuj, ntuj.
1. Los ntawm Video Signal mus rau Visible Xim
Yeej, lub TV tau txais cov duab teeb liab hauv daim ntawv digital lossis analog (piv txwv li, HDMI, digital broadcasts, lossis streaming media). Cov teeb liab no nqa cov ntaub ntawv luminance (brightness) thiab chrominance (xim), feem ntau yog hom ntawv zoo li YCbCr lossis RGB. Ua ntej tso tawm rau ntawm qhov screen, cov ntaub ntawv no yuav tsum tau ua los ntawm lub processor duab (video processor). Lub processor no yog lub luag haujlwm rau ntau yam: txo suab nrov, txhim kho qhov ntse, txhim kho kev txav mus los, thiab qhov tseem ceeb tshaj plaws hauv qhov no - kev hloov xim thiab kev kos duab kom haum rau lub vaj huam sib luag cov yam ntxwv.
Hauv ntau qhov chaw video, cov ntaub ntawv xim raug encoded nrog subsampling, xws li 4:2:0, rau kev ua haujlwm zoo. Qhov no txhais tau tias cov xim meej yog compressed ntau dua li qhov kaj meej. Lub TV ces ua chroma upsampling kom "rov qab" qhov kev daws teeb meem xim, tiv thaiv cov zaub kom tsis txhob tshwm sim pixelated nrog cov ntawv me me lossis cov kab nyias nyias xim.
2. LCD Vaj Huam Sib Luag, LED Backlight, thiab Lub Luag Haujlwm ntawm Cov Lim Xim
Feem ntau cov TV LED siv cov LCD (Liquid Crystal Display) panels. Cov LCD panels tsis tso tawm lub teeb lawv tus kheej, tab sis hloov chaw tswj hwm qhov ntau npaum li cas lub teeb los ntawm LED backlight tso cai los ntawm. Lub teeb los ntawm lub backlight no feem ntau yog dawb (LED dawb) lossis ib qho kev sib xyaw ua ke spectrum. Lub teeb ces dhau los ntawm RGB (liab, ntsuab, thiab xiav) lim xim ntawm txhua subpixel. Qhov sib xyaw ua ke ntawm peb subpixels no tsim ntau lab xim.
Qhov zoo ntawm xim yog cuam tshuam los ntawm:
- LED backlight spectrum: Qhov "huv dua" qhov spectrum, qhov dav dua ntawm cov xim (gamut) uas tuaj yeem ua tiav.
- Qhov zoo ntawm cov lim xim: Lub lim zoo tuaj yeem tsim cov xim liab, ntsuab, thiab xiav ntshiab dua.
- Kev ua tau zoo ntawm vaj huam sib luag: Muaj xws li lub peev xwm thaiv lub teeb rau cov xim tsaus thiab kev ruaj khov ntawm lub kaum sab xis saib.
Hauv cov TVs nruab nrab thiab siab kawg, ntau lub tuam txhab tsim khoom siv cov thev naus laus zis xws li Quantum Dot (QLED) los ua kom lub teeb ci ntsa iab kom cov xim nplua nuj dua thiab ntau qhov gamut dav dua.
3. Qhov Chaw Xim thiab Gamut
Lub TV lub tshuab ua xim yuav tsum hloov kho qhov screen kom haum rau tus qauv xim tshwj xeeb. Qee cov qauv feem ntau yog:
– sRGB / Rec.709: Feem ntau rau HD TV tshaj tawm thiab feem ntau SDR (Standard Dynamic Range) cov ntsiab lus.
– DCI-P3: Siv dav hauv cov ntsiab lus xinesmas thiab qee cov ntsiab lus HDR.
– Rec.2020: Lub hom phiaj rau cov ntsiab lus UHD/HDR nrog ntau yam, txawm hais tias tsis yog txhua lub TV muaj peev xwm ua tiav tag nrho.
Thaum cov ntsiab lus los txog rau hauv Rec.709, lub TV yuav teeb cov xim kom pom tseeb rau ntawm lub vaj huam sib luag. Txawm li cas los xij, yog tias cov ntsiab lus yog HDR nrog lub hom phiaj gamut dav dua, lub TV yuav tsum ua qhov kev teeb tsa xim gamut kom hloov kho cov ntaub ntawv xim rau lub vaj huam sib luag lub peev xwm. Yog tias qhov kev teeb tsa no tsis raug, cov xim tuaj yeem zoo li oversaturated lossis txawm tias ntxuav tawm.
4. Qhov tob ntawm qhov ntsis thiab kev hloov xim
Cov xim digital yog sawv cev los ntawm cov lej. Qhov tob ntawm qhov bit ntau dua, qhov gradation du dua. Cov TV niaj hnub no feem ntau txhawb nqa:
- 8-ntsis (kwv yees li 16,7 lab xim) rau SDR,
- 10-ntsis (ntau tshaj 1 billion xim sib txawv) rau HDR,
- Kuj tseem muaj lub vaj huam sib luag "8-bit + FRC" (Frame Rate Control) uas ua rau 10-bit nrog kev sib hloov sijhawm.
Lub tshuab ua xim kuj ua haujlwm los txo cov xim sib txawv, cov kab gradient pom tseeb hauv ntuj lossis cov duab ntxoov ntxoo mos. Cov yam ntxwv zoo li dithering thiab gradation smoothing tuaj yeem pab tsim cov xim hloov pauv du.
5. Kev Sib Npaug Dawb, Kub Xim, thiab Gamma
Qhov tseeb ntawm xim tsis yog hais txog xim liab-ntsuab-xiav xwb, tab sis kuj yog hais txog qhov "dawb" zoo. Cov xim dawb uas xiav dhau ua rau daim duab zoo li txias, thaum cov xim dawb uas daj dhau ua rau nws sov. Feem ntau cov TV muaj cov hom kub xim xws li "Tshaj," "Ib txwm," thiab "Sov." Los ntawm lub neej ntawd, rau kev saib cov yeeb yaj kiab thiab lwm yam ntsiab lus kom raug, lub hom phiaj feem ntau yog D65 (kwv yees li 6500K).
Tsis tas li ntawd xwb, muaj ib qho tseem ceeb hu ua gamma (rau SDR) lossis transfer curve, xws li PQ (ST.2084) thiab HLG (rau HDR). Gamma tswj cov midtones li cas. Yog tias gamma siab dhau, daim duab yuav tsaus dua thiab sib piv ntau dua; yog tias nws qis dhau, daim duab yuav zoo li ntxuav tawm.
Lub kaw lus ua xim yuav sib xyaw ua ke qhov sib npaug dawb, gamma, thiab kev tswj xim kom ntseeg tau tias qhov kawg ua tau raws li tus neeg siv cov qauv lossis kev nyiam.
6. Lub Tshuab Tswj Xim (CMS)
Ntau lub TV niaj hnub no muab CMS, uas yog ib qho system rau kev kho cov xim kom ntxaws ntxiv, feem ntau suav nrog:
- Xim (xim),
- Kev saturation,
- Luminance (xim ci).
CMS tso cai rau kev hloov kho cov xim thawj (RGB) thiab xim theem ob (CMY) kom ze li cov qauv siv. Hauv kev ntsuas kev tshaj lij, cov kws kho tshuab siv lub colorimeter lossis spectroradiometer los ntsuas qhov tso zis ntawm lub vaj huam sib luag, tom qab ntawd kho CMS thiab qhov sib npaug dawb kom ua tiav qhov yuam kev xim qis (Delta E).
7. Kev Ua HDR thiab Kev Qhia Txog Lub Suab
HDR (High Dynamic Range) nthuav qhov ci thiab ntau yam xim, ua rau pom tseeb dua ntawm lub teeb thiab tsaus ntuj. Txawm li cas los xij, tsis yog txhua lub TV muaj tib lub peev xwm ci ntsa iab. Yog li ntawd, TVs ua qhov kev teeb tsa suab: teeb tsa lub teeb liab HDR, tej zaum tsim rau 1000–4000 nits (lossis ntau dua), kom phim lub peev xwm ntawm lub vaj huam sib luag, xws li 500–1000 nits.
Kev teeb tsa xim muaj feem cuam tshuam nrog xim, vim tias hauv HDR, kev sib xyaw xim feem ntau hloov pauv thaum qhov ci ntsa iab nce ntxiv. Qhov no yog vim li cas HDR cov txheej txheem ua xim yuav tsum tswj cov xim zoo li ntuj hauv thaj chaw ci, tiv thaiv lawv kom tsis txhob raug ntxuav tawm lossis "kub hnyiab."
Cov hom ntawv HDR feem ntau muaj xws li:
- HDR10 (cov ntaub ntawv metadata zoo li qub),
- HDR10+ thiab Dolby Vision (dynamic metadata),
– HLG (feem ntau siv rau kev tshaj tawm).
Cov ntaub ntawv metadata dynamic tso cai rau lub TV kho qhov kev sib hloov suab rau txhua qhov xwm txheej lossis ib thav duab kom cov xim thiab cov ntsiab lus zoo dua.
8. Kev Ua Kom Dimming Hauv Zos thiab Nws Cov Nyhuv Rau Xim
Cov TV LED uas muaj qhov tsaus ntuj hauv zos (tshwj xeeb tshaj yog Full Array Local Dimming/FALD) tuaj yeem tsaus cov cheeb tsam tshwj xeeb ntawm lub teeb ci ntsa iab kom zoo dua qub. Txawm li cas los xij, lub kaw lus no kuj cuam tshuam rau kev pom xim. Yog tias cov txheej txheem tsaus ntuj hauv zos ua haujlwm hnyav dhau, cov xim meej hauv cov cheeb tsam tsaus ntuj tuaj yeem ploj lossis tawg paj (lub teeb "tawm" nyob ib puag ncig cov khoom ci). Yog li ntawd, kev ua xim thiab kev tswj lub teeb ci ntsa iab yuav tsum ua haujlwm sib haum xeeb kom tswj tau cov xim nplua nuj hauv cov duab ntxoov ntxoo yam tsis muaj kev cuam tshuam rau qhov sib txawv.
9. Hom Duab thiab Xim "Saj"
Ntau lub TV muaj hom xws li Vivid, Standard, Cinema, lossis Filmmaker Mode. Hom Vivid feem ntau ua rau kom saturation, contrast, thiab sharpness ntau dua kom nws nyiam nyob rau hauv cov khw muag khoom uas muaj teeb pom kev zoo, tab sis feem ntau txo qhov tseeb ntawm xim. Cinema lossis Filmmaker Mode feem ntau yuav ze rau cov qauv tsim yeeb yaj kiab thiab xa cov xim ntuj dua.
Tsis tas li ntawd xwb, qee lub TV muaj cov yam ntxwv ntxiv xws li "Live Color," "Color Enhancer," lossis "Dynamic Contrast," uas hloov kho cov xim. Cov yam ntxwv no tuaj yeem pab tau rau qee cov ntsiab lus, tab sis rau cov neeg siv uas tsom mus rau qhov tseeb, lawv feem ntau zoo tshaj plaws tso tseg.
10. Txoj kev
Lub tshuab ua xim hauv lub TV LED yog ib qho txheej txheem nyuaj uas hloov cov ntaub ntawv video mus rau hauv qhov chaw zoo, raug, thiab zoo nkauj. Txij li kev hloov pauv hom xim, gamut mapping, qhov chaw sib npaug dawb, gamma, CMS, mus rau HDR ua thiab tone mapping - txhua yam ua lub luag haujlwm hauv kev txiav txim siab qhov zoo ntawm qhov muag. Qhov tshwm sim kawg kuj tseem cuam tshuam los ntawm lub peev xwm ntawm lub cuab yeej: backlight spectrum, xim lim zoo, qhov tob ntawm vaj huam sib luag, thiab local dimming algorithm.
Kev nkag siab txog kev ua haujlwm ntawm cov xim pab cov neeg siv xaiv hom duab zoo, teeb tsa cov kev teeb tsa kom paub ntau ntxiv, lossis txawm tias kho kom tau cov xim ze rau qhov piv txwv. Ua li no, LED TVs tsis yog tsuas yog tso saib cov duab "ci", tab sis kuj tseem muaj cov xim ci ntsa iab, sib npaug uas phim cov ntsiab lus ntawm tus tsim cov ntsiab lus.
