22/04/22I-Dark Signal Non-Uniformity (DSNU) isilinganiso sezinga lokuhlukahluka okuzimela ngesikhathi ngemuva kwesithombe sekhamera. Ihlinzeka ngenkomba yezinombolo eqinile yekhwalithi yaleso sithombe sangemuva, mayelana namaphethini noma izakhiwo ezingaba khona ngezinye izikhathi.
Emfanekisweni wokukhanya okuphansi, ikhwalithi yangemuva yekhamera ingaba isici esibalulekile. Uma zingekho izigameko zezithombe kukhamera, izithombe ezitholiwe ngokuvamile ngeke zibonise amanani ephikseli angu-0 amaleveli ampunga (ADU). Inani 'le-offset' livame ukuba khona, elifana namazinga ampunga angu-100, ikhamera ezowabonisa uma kungekho ukukhanya, kanye noma kususwe umthelela womsindo esilinganisweni. Kodwa-ke, ngaphandle kokulinganisa nokulungisa ngokucophelela, kungase kube khona ukuhluka okuthile ukusuka ku-pixel kuye kwephikseli kuleli nani elingashintshiwe. Lokhu kuhluka kubizwa ngokuthi 'Iphethini Engaguquki Noise'. I-DNSU imele ububanzi balo msindo wephethini engashintshi. Imele ukuchezuka okujwayelekile kwamanani e-pixel offset, akalwa ngama-electron.
Kumakhamera amaningi ezithombe ezinokukhanya okuphansi, i-DSNU ngokuvamile ingaphansi kuka-0.5e-. Lokhu kusho ukuthi ezinhlelweni zokusebenza ezinokukhanya okumaphakathi noma okuphezulu ezinamakhulu noma izinkulungwane zamafotoni athwetshulwa ngephikseli ngayinye, lo msindo onikelayo awunaki nhlobo. Impela, ezinhlelweni zokukhanya okuphansi futhi, ukuhlinzeka nge-DSNU iphansi kunomsindo ofundiwe wekhamera (imvamisa engu-1-3e-), lo msindo wephethini engashintshi cishe awunakudlala indima kwikhwalithi yesithombe.
Kodwa-ke, i-DSNU ayiyona into emele iphelele yomsindo wephethini engashintshi, njengoba yehluleka ukuthwebula izici ezimbili ezibalulekile. Okokuqala, amakhamera e-CMOS angabonisa amaphethini ahlelekile kulokhu kuhluka kwe-offset, ngokuvamile ngendlela yamakholomu amaphikseli ahluka kwamanye ngevelu yawo ye-offset. Lo msindo we-'Fixed Column Noise' ubonakala kakhulu emehlweni ethu kunomsindo ongahlelekile, kodwa lo mehluko awumelwe inani le-DSNU. Lawa ma-artefacts ekholomu angase avele ngemuva kwezithombe ezikhanyayo eziphansi kakhulu, njengalapho isignali etholiwe ingaphansi kwama-photo-electron angu-100. Ukubuka isithombe 'sokuchema', isithombe esikhiqizwa ikhamera ngaphandle kokukhanya, sizokuvumela ukuthi uhlole ukubakhona komsindo wephethini ehlelekile.
Okwesibili, kwezinye izimo, ukuhluka okuhleliwe kokuhlehlisa kungancika esikhathini, kuhluke kuhlaka olulodwa kuya kolunye. Njengoba i-DSNU ibonisa kuphela ukuhluka okuzimela ngesikhathi, lokhu akufakiwe. Ukubuka ukulandelana kwezithombe ezichemile kuzokuvumela ukuthi uhlole ukubakhona komsindo wephethini oncike esikhathini.
Njengoba kuphawuliwe nokho, i-DSNU nokuhluka kwe-background offset ngeke kube into ebalulekile ezinhlelweni zokukhanya okuphakathi nendawo ukuya kweziphezulu ezinezinkulungwane zama-photon ngephikseli ngayinye, njengoba lezi zimpawu zizoba namandla kakhulu kunokwehluka.
