Kawm Ntxiv Txog Dynamic Range thiab Tonal Khwv Nyob Hauv Duab
Yog tias koj tau xav li cas txog kev sib txawv npaum li cas thiab cov khoom tonal rau koj cov teeb meem digital photography, koj tsis yog ib leeg. Cov lus ob kab lus no yuav ua rau me ntsis ruam rau thawj zaug, tiam sis koj tuaj yeem txhim kho koj tus DSLR photography los ntawm kev kawm seb lawv ua haujlwm li cas.
Qhov Dynamic Range yog dab tsi?
Tag nrho cov koob yees duab DSLR muaj lub cim ntim uas kaw cov duab. Qhov dynamic range ntawm ib lub rhais fab yog txhais los ntawm ntau tshaj plaws tau teeb liab uas nws tau tsim faib los ntawm lub teeb meem tsawg tshaj plaws.
Lub teeb liab yog tsim thaum lub koob yees duab duab sensor pixels ntes photons, uas lawv mam li tig mus ua hluav taws xob.
Qhov no txhais tau hais tias cov koob yees duab nrog ntau qhov loj zog tuaj yeem ntes cov ntsiab lus thiab cov duab ntxoov ntxoo tib lub sij hawm thiab ntau dua. Los ntawm RAW shooting, qhov dynamic range ntawm tus sensor yog fwm, whereas JPEGs yuav clip cov ntsiab lus vim cov ntaub ntawv compression.
Raws li twb tau hais, pixels ntawm lub sensor sau photons thaum raug tus duab. Lub zog ntau dua, cov photons ntau sau. Vim li no, cov pixels uas khaws cov zog seem ntawm cov duab sau tag nrho lawv cov photons sai dua li cov pixels uas khaws cov khoom tsaus ntuj. Qhov no tuaj yeem ua rau muaj kev phom sij ntawm phaus, uas tuaj yeem ua rau blooming .
Cov teeb meem nrog kev sib txawv ntawm ntau qhov kev ua tau raug pom hauv cov duab sib txawv. Yog tias lub teeb ci hnyav heev, lub koob yees duab kuj yuav 'ua kom nrov' qhov highlights thiab tawm tsis muaj kev nthuav dav hauv cov cheeb tsam dawb ntawm daim duab. Thaum tib neeg lub qhov muag yuav kho tau qhov sib txawv thiab cov lus qhia, lub koob yees duab tsis tuaj yeem. Thaum qhov no tshwm sim, peb tuaj yeem kho qhov kis tau los ntawm kev siv ceev xwmphem lossis ntxiv ntau ntxiv lub teeb kom txo qhov sib txawv ntawm qhov kev kawm.
DSLRs muaj zog loj tshaj li cov taw tes thiab tua cov koob yees duab vim lawv cov sensors muaj pixels loj. Qhov no txhais tau hais tias lub pixels muaj sijhawm txaus sau cov photons rau ob sab thiab tsaus nti ntawm daim duab tsis muaj txeej.
Tonal ntau npaum li cas?
Tonal khwv yees ntawm ib cov duab muaj feem xyuam nrog cov xov tooj ntawm cov tones nws muaj los piav txog qhov txawv ntawm ntau yam.
Qhov ob hom yog muaj feem xyuam. Ib qhov kev ua loj loj nrog rau Analog rau Digital Converter (ADC) ntawm yam tsawg 10 khoom tuaj yeem sib npaug rau ntau hom tonal. (ADC yog ib feem ntawm kev hloov pixels ntawm lub digital sensor rau cov duab nyeem tau.) Zoo sib xws, yog ib lub sensor nrog ib tug ADC 10 khoom tuaj yeem tso tau ntau tus tones, nws yuav muaj qhov loj dynamic ntau.
Vim hais tias tib neeg lub zeem muag tsis yog-tawm, tog twg los yog ob qho tib si dynamic thiab tonal ntau yuav tsum tau muab los ntawm lub tonal curve kom muaj kev lom zem ntxiv rau lub qhov muag. Qhov tseeb tiag, RAW kev hloov cov kev pab cuam los yog hauv lub koob yees duab yees yuav siv tus vuam siv S-zoo li tus cwj pwm mus rau cov ntaub ntawv kom thiaj li ua kom pom qhov sib txawv loj dua nyob rau hauv ib txoj kev uas pom kev zoo siab hauv cov ntawv luam los yog ntawm lub monitor.