Kunzwisisa Nyquist Sampling: Kuenzanisa Optical uye Camera Resolution |

Mukufungidzira kwedhijitari, zviri nyore kufunga kuti resolution yepamusoro inoreva otomatiki mifananidzo iri nani. Vagadziri vekamera vanowanzo tengesa masisitimu zvichienderana nekuverenga megapixel, nepo vagadziri vemalenzi vachiratidza simba rekugadzirisa uye kupinza. Asi, mukuita, chimiro chemufananidzo hachitsamiri chete pane zvakatemwa lens kana sensor yega yega asi zvakare kuti inonyatsoenderana sei.

Apa ndipo panopinda Nyquist sampling. Pakutanga musimboti kubva pakugadziriswa kwemasaini, chirevo chaNyquist chinoisa iyo theoretical system yekutora ruzivo nemazvo. Mukufungidzira, inova nechokwadi chekuti iyo optical resolution inounzwa nelenzi uye iyo dijitari resolution yekamera sensor inoshanda pamwe zvakabatana.

Ichi chinyorwa chinoburitsa sampling yeNyquist mumamiriro ekufungidzira, inotsanangura chiyero pakati pekugadziriswa kwemaziso nekamera, uye inopa nhungamiro inoshanda yezvishandiso kubva pakutora mifananidzo kusvika kukufungidzira kwesainzi.

Chii chinonzi Nyquist Sampling?

Mufananidzo 1: Iyo Nyquist sampling theorem

Pamusoro:Chiratidzo che sinusoidal (cyan) chinopimwa, kana kuti sampled, panzvimbo dzakawanda. Iyo grey refu-dashed mutsara inomiririra 1 kuyerwa kutenderera kweiyo sinusoidal chiratidzo, ichitora chete masaini peaks, ichivanza zvachose chimiro chechokwadi chechiratidzo. Iyo tsvuku yakatsetseka yakatsetseka inobata pazviyero 1.1 pamuenzaniso, ichiratidza sinusoid asi ichimiririra zvisizvo kuwanda kwayo. Izvi zvakafanana neMoiré pateni.

Pazasi:Chete kana 2 samples dzatorwa padenderedzwa (yepepuru ine doti mutsara) ndipo iyo chaiyo yechiratidzo chinotanga kutorwa.

Iyo Nyquist sampling theorem ndiyo musimboti wakajairika mukati mechiratidzo chekugadzirisa mune zvemagetsi, audio processing, imaging uye mamwe minda. Iyo theorem inojekesa kuti kuvakazve yakapihwa frequency muchiratidzo, kuyerwa kunofanirwa kuitwa kanenge kaviri iyo frequency, inoratidzwa muFigure 1. Muchiitiko chekugadzirisa kwedu kwemaziso, izvi zvinoreva kuti chinhu chedu nzvimbo yepikisi saizi inofanira kunge iri pahafu yediki diki ruzivo rwatiri kuedza kutora, kana, kana iri maikorosikopu, hafu yekugadziriswa kwema microscope.

Mufananidzo 2: Nyquist sampling ine sikweya pixels: yekutarisa nyaya

Uchishandisa kamera ine gidhi yemapikiseli emativi, iyo 2x sampling factor yeNyquist theorem inongotora nemazvo ruzivo rwakanyatsoenderana kune pixel grid. Kana uchiedza kugadzirisa zvimiro pakona kugidhi yepixel, saizi yepixel inoshanda yakakura, inosvika √2 yakakura pane diagonal. Sampling rate inofanirwa kunge iri 2√2 times the inodiwa spatial frequency kutora ruzivo pa45o kune pixel grid.

Chikonzero cheizvi chinoitwa pachena nekufunga kweMufananidzo 2 (yepamusoro hafu). Fungidzira saizi yepixel yakamisirwa kugadziriso yemaziso, ichipa nhongonya dzenzvimbo mbiri dzakavakidzana, kana chero ruzivo rwatiri kuyedza kugadzirisa, imwe neimwe pixel yavo. Kunyangwe izvi zvichizoonekwa zvakaparadzana, hapana chinoratidza muzviyero zvinokonzeresa kuti iwo maviri akapatsanurwa epamusoro - uye zvekare tsananguro yedu ye "kugadzirisa" haina kusangana. Pixel iri pakati inodiwa, inobata chirongo chechiratidzo. Izvi zvinowanikwa kuburikidza nekupeta kaviri mwero wesampling yepakati, kureva kudzika nehafu saizi yepikisi yechinhu.

Optical Resolution vs. Camera Resolution

Kuti tinzwisise kuti Nyquist sampling inoshanda sei mukufungidzira, tinoda kusiyanisa pakati pemhando mbiri dzekugadzirisa:

● Optical Resolution: Inosarudzwa nelens, optical resolution inoreva kukwanisa kwayo kubereka zvakadzama. Zvinhu zvakadai semhando yelens, aperture, uye diffraction inoisa muganhu uyu. Iyo modulation transfer function (MTF) inowanzo shandiswa kuyera kuti lenzi inofambisa sei musiyano pane dzakasiyana siyana dzenzvimbo.

● Kugadziriswa kwekamera: Inotarirwa ne sensor, kugadziriswa kwekamera kunoenderana nehukuru hwepixel, pitch pitch, uye zviyero zvesenso. Chimiro chepixel cheCMOS kamerainotsanangura zvakananga iyo Nyquist frequency, iyo inotaridza iyo yakanyanya ruzivo iyo sensor inogona kutora.

Kana zviviri izvi zvikasaenderana, matambudziko anomuka. Iyo lens inodarika simba rekugadzirisa re sensor inonyatso "kuraswa", sezvo sensor haigone kutora zvese zvese. Sezvineiwo, sensor yepamusoro-resolution yakabatanidzwa neakaderera-mhando lens inoguma mumifananidzo isinganatsirike kunyangwe akawanda megapixels.

Maitiro ekuenzanisa Optical uye Kamera Resolution

Kuenzanisa optics uye sensors zvinoreva kuenzanisa iyo Nyquist frequency ye sensor ine optical cutoff frequency yelens.

● Iyo Nyquist frequency yekamera sensor inoverengerwa se 1 / (2 × pixel pitch). Izvi zvinotsanangura iyo yepamusoro nzvimbo frequency iyo sensor inogona kuenzanisa pasina aliasing.
● The optical cutoff frequency inobva pane lens maitiro uye diffraction.

Kuti uwane mhedzisiro yakanakisa, iyo sensor's Nyquist frequency inofanirwa kuenderana kana zvishoma kudarika kugona kwekugadzirisa lens. Mukuita, mutemo wakanaka wegunwe ndeyekuona kuti pixel pitch inenge hafu yediki inogadziriswa saizi yelens.

Semuyenzaniso, kana lenzi richikwanisa kugadzirisa zvinhu kusvika ku4 micrometers, ipapo sensor ine pixel saizi ye ~ 2 micrometer inodzikamisa system zvakanaka.

Kufananidza Nyquist neKamera Resolution & Dambudziko reMapikicha eSquare

Kutengeserana nekudzikira kwechinhu nzvimbo pixel saizi inodzikiswa kugona kuunganidza mwenje. Saka zvakakosha kuenzanisa kudiwa kwekugadzirisa uye kwekuunganidza chiedza. Pamusoro pezvo, hombe yenzvimbo nzvimbo pixel saizi inowanzo fambisa nzvimbo yakakura yekuona yechinhu chekufungidzira. Kune maapplication ane chimwe chinoda kugadziriswa kwakanaka, 'rule of thumb' optimum balance inonzi inorohwa sezvizvi: Saizi yepixel yechinhu, kana ichipetwa nechimwe chinhu ku account yeNyquist, inofanira kuenzana neoptical resolution. Huwandu uhu hunonzi camera resolution.

Kuenzanisa optics uye ma sensors anowanzo kudzika pasi kuti ave nechokwadi chekuti iyo inoshanda sampling resolution yekamera inofanana neiyo Optical resolution muganho welens. A system inonzi "inofananidza Nyquist" apo:

Camera resolution = Optical resolution

Iko kugadzirisa kwekamera kunopihwa ne:

Chinhu chekuzvidavirira kuNyquist iyo inowanzokurudzirwa ndeye 2.3, kwete 2. Chikonzero cheizvi ndecheiyi.

Kamera pixels ndeye (kazhinji) sikweya, uye yakarongwa pane 2-D grid. Saizi yepixel sezvainotsanangurwa kuti ishandiswe muequation yakatarisana inomiririra hupamhi hwemapikisi ari padyo nematemo egridi iyi. Kana maficha atiri kuedza kugadzirisa akanyepa chero pakona kunze kwekuwanda kwakakwana kwe90 ° kune iyi grid, saizi yepixel inoshanda ichave yakakura, kusvika √2 ≈ 1.41 yakapetwa saizi yepixel pa45 °. Izvi zvinoratidzwa muMufananidzo 2 (hafu yepasi).

Izvo zvinokurudzirwa zvinoenderana neNyquist criterion mune zvese zvinongedzo zvinozove 2√2 ≈ 2.82. Zvisinei, nekuda kwekutengeserana kwakambotaurwa pakati pekugadzirisa uye kuunganidza chiedza, kukosha kwekugadzirisa kwe2.3 kunokurudzirwa semutemo wegunwe.

Basa reNyquist Sampling muKufananidza

Nyquist sampling ndiye muchengeti wegedhi rekuvimbika kwemufananidzo. Kana iyo sampling rate inowira pasi peNyquist muganho:

● Kuenzanisira zvishoma → kunokonzeresa zita rezita: mashoko emanyepo, mipendero yakakombama, kana mapatani emoiré.

● Oversampling → inotora data rakawanda kupfuura rinogona kuendeswa neoptics, zvichiita kuti kudzoka kuderera: mafaira makuru uye kudiwa kwepamusoro pekugadzirisa pasina kuvandudzwa kunooneka.

Sampling chaiyo inovimbisa kuti mifananidzo yakapinza uye yechokwadi kune chokwadi. Inopa chiyero pakati pekupinza kwemaziso uye kubatwa kwedhijitari, kudzivirira kuraswa kugadzirisa kune rimwe divi kana nhema dzakagadzirwa kune rimwe.

Inoshanda Zvikumbiro

Nyquist sampling haingori dzidziso - ine zvakakosha mashandisiro pamaitiro ekufungidzira:

● Maikorosikopu:Vatsvaguri vanofanirwa kusarudza masensa anosample kanenge kaviri iyo diki diki inogadziriswa neiyo chinangwa lens. Kusarudza zvakanakamicroscopy kamerayakakosha, sezvo saizi yepixel inofanirwa kuenderana nediffraction-inogumira kugadziriswa kwechinangwa chemicroscope. Marabhoritari emazuva ano anowanzofarirasCMOS makamera, iyo inopa chiyero chekunzwa, dynamic range, uye yakanaka pixel zvimiro zvepamusoro-kuita biological imaging.

● Kutora Mifananidzo:Kubatanidza ma-high-megapixel sensors nemalenzi asingakwanise kugadzirisa zvakaenzana zvakaenzana zvinokonzeresa kuvandudza kusingaite mukupinza. Nyanzvi mafoto anoyera lenzi uye makamera kudzivirira kutambisa kugadzirisa.

● Machine Vision &Scientific MakameraMukutonga kwemhando uye nekuongorora kwemaindasitiri, kushaikwa zvidiki zvidiki nekuda kwe undersampling zvinogona kureva kuti akaremara zvikamu hazvionekwe. Oversampling inogona kushandiswa nemaune kudhijitari zoom kana kukwidziridzwa kugadzirisa.

Nguva Yekufananidza Nyquist: Kuwedzeredza uye Undersampling

Nyquist sampling inomiririra yakaringana, asi mukuita, ekufungidzira masisitimu anogona kupfuudza nemaune kana kuita mashoma zvichienderana nekushandisa.

Chii chinonzi Undersampling

Panyaya yezvishandiso uko kunzwisiswa kwakakosha pane kugadzirisa zvidiki zveakanakisa ruzivo, kushandisa chinhu nzvimbo pixel saizi yakakura pane inodiwa neNyquist inogona kutungamira kune yakakura kuunganidzwa kwechiedza. Izvi zvinonzi undersampling.

Izvi zvinopa ruzivo rwakanaka, asi zvinogona kubatsira kana:

● Sensitivity inokosha: mapikseli makuru anounganidza chiedza chakawanda, anovandudza chiratidzo-ku-ruzha reshiyo mumifananidzo yakaderera.
● Kumhanya kunokosha: mapixels mashoma anoderedza nguva yekuverenga, zvichiita kuti uwane nekukurumidza.
● Kushanda kwedata kunodiwa: madiki madiki mafaira anodiwa mubandwidth-limited systems.

Muenzaniso: Mukufungidzira kwecalcium kana voltage, masaini anowanzo kuenzaniswa nematunhu anofarira, saka kuita zvishoma kunonatsiridza kuunganidzwa kwemwenje pasina kukanganisa mhedzisiro yesainzi.

Chii chinonzi Oversampling

Sezvineiwo, maapplication mazhinji ayo ekugadzirisa zvakanakisa kwakakosha, kana maapplication anoshandisa mushure-yekutora nzira dzekuongorora kuti adzore rumwe ruzivo kupfuura iyo diffraction muganho, anoda mapikisi ekufungidzira madiki pane anodiwa naNyquist, anonzi oversampling.

Nepo izvi zvisingawedzere yechokwadi Optical resolution, inogona kupa zvakanakira:

● Inogonesa zoom yedhijitari ine kurasikirwa kwemhando shoma.
● Inovandudza post-processing (semuenzaniso, deconvolution, denoising, super-resolution).
● Rinoderedza zita remazita kana mapikicha akadzikiswa gare gare.

Muenzaniso: Mune microscope, yakakwirira-resolution sCMOS kamera inogona kupfuudza zvimiro zvemaserura kuitira kuti computational algorithms ikwanise kuburitsa zvinhu zvakanaka kupfuura muganho wediffraction.

Mafungiro Akajairika

1, Mamwe mamegapixel anogara achireva mifananidzo yakapinza.
Kwete chokwadi. Kupinza kunotsamira pane ese ari maviri simba rekugadzirisa lens uye kana ma sensor samples zvakakodzera.

2, Chero lenzi yakanaka inoshanda nemazvo nechero yakakwira-resolution sensor.
Mutambo usina kunaka pakati pekugadzirisa lens uye pixel pitch inodzikamisa kuita.

3, Sampling yeNyquist inongoshanda mukugadzirisa zviratidzo, kwete kufungidzira.
Kusiyana neizvi, kufungidzira kwedhijitari inzira yekuenzanisira, uye Nyquist yakakosha pano sekuteerera kana kutaurirana.

Mhedziso

Nyquist sampling inopfuura yekubatisa masvomhu - ndiyo musimboti unovimbisa kugadzirisa kwemaziso uye kwedhijitari kushanda pamwechete. Nekugadzirisa simba rekugadzirisa remalensi pamwe nesampling kugona kwemasensa, masystem ekufungidzira anowana kujeka kwakanyanya pasina zvigadzirwa kana kutambisa simba.

Kune nyanzvi muminda dzakasiyana senge microscope, nyeredzi, kutora mafoto, uye muchina kuona, kunzwisisa Nyquist sampling kwakakosha pakugadzira kana kusarudza masisitimu ekufungidzira anopa mhedzisiro yakavimbika. Pakupedzisira, kunaka kwemufananidzo kunouya kwete kubva pakusundidzira kumwe kutsanangurwa kusvika kune yakanyanyisa asi kubva pakuwana chiyero.

FAQs

Chii chinoitika kana Nyquist sampling ikasagutsikana mukamera?
Kana iyo sampling chiyero ichidonha pazasi peNyquist muganho, iyo sensor haigone kumiririra yakanaka ruzivo nenzira kwayo. Izvi zvinoguma neaasing, inoratidzika seyakakombama kumucheto, moiré mapatani, kana manyepo maumbirwo asipo pachiitiko chaicho.

Saizi yepixel inobata sei Nyquist sampling?
Mapikisiki madiki anowedzera iyo Nyquist frequency, zvichireva kuti sensor inogona kufungidzira kugadzirisa zvakanangana. Asi kana lenzi isingakwanise kuunza iyo nhanho yekugadziriswa, iwo ekuwedzera pixels anowedzera kukosha kushoma uye anogona kuwedzera ruzha.

Ko Nyquist sampling yakasiyana yemonochrome vs. color sensors?
Ehe. Mune monochrome sensor, yega pixel samples inopenya zvakananga, saka iyo inoshanda Nyquist frequency inofanana nepixel pitch. Mune sensor yemavara ine Bayer sefa, imwe neimwe chiteshi chemavara haina kusampled, saka iyo inoshanda kugadzirisa mushure medemosaicing yakadzikira zvishoma.

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