Spectral sensitivity and color formats

Transcription

1 FirWir camras Spctral snsitivity and color formats At th "input" of a camra, w hav a CCD chip. It transforms photons into lctrons. Th spctral snsitivity of this transformation is an important charactristic of th "camra input". At th camra's output, w xcpt an imag data stram with a color format, such as "Y (Mono)" for monochrom camras, or "RGB" for color camras. In this whit papr, th input and output bhavior of Th Imaging Sourc FirWir camras will b xamind. Plas not: It is th rsponsibility of an on-sit nginr to corrctly intgrat FirWir camras into ral applications. Contnt Ovrviw CCD chips (monochrom) CCD chips (color) Bayr filtr IR cut filtr Optical low pass filtr (OLPF) Color formats Th Imaging Sourc FirWir camras EUROPEAN HEADQUARTERS Th Imaging Sourc Europ GmbH Sommrstrass 36, D Brmn, Grmany support@u.thimagingsourc.com Phon: US HEADQUARTERS Th Imaging Sourc, LLC 7257 Pinvill-Matthws Road, Charlott, NC support@us.thimagingsourc.com Phon: USA Toll Fr: USA All product and company nams in this documnt may b tradmarks and tradnams of thir rspctiv ownrs and ar hrby acknowldgd. Th Imaging Sourc Europ GmbH cannot and dos not tak any rsponsibility or liability for any information containd in this documnt. Th sourc cod prsntd in this documnt is xclusivly usd for didactic purposs. Th Imaging Sourc dos not assum any kind of warranty xprssd or implid, rsulting from th us of th contnt of this documnt or th sourc cod. Th Imaging Sourc Company rsrvs th right to mak changs in spcifications, function or dsign at any tim and without prior notic. Last updat: March 26 Copyright 26 Th Imaging Sourc Europ GmbH All rights rsrvd. Rprint, also in parts, only allowd with prmission of Th Imaging Sourc Europ GmbH. All wights and dimnsions ar approximat. FirWir Kamras - Spctral snsitivity and color formats

2 Ovrviw At th "input" of a camra, w hav a CCD chip. Som camras also hav an IR cut filtr and an optical low pass filtr (OLPF). Th camra lctronics transform th CCDs contnt into an imag data stram with a color format, such as "Y (Mono)" for monochrom camras, or "RGB" for color camras. Ths four componnts dtrmin th camra's spctral bhavior in four diffrnt ways: Th CCD chip transforms photons into lctrons (photolctric ffct). A Bayr filtr. insid th color CCDs is rsponsibl for th cration of colors. IR cut filtr OLPF CCD chip Camra lctronics In contrast to th human y, CCD chips ar also snsitiv to nar infrard light. In th cas of color camras this would lad to a prdominanc of rd. An IR cut filtr corrcts this situation. If th objct that is to b acquird shows fin and rgular structurs, moiré pattrns may occur in th rsulting imag. An optical low pass filtr (OLPF) rducs this ffct. Th camra lctronics nhanc th CCD chips' raw data. This nhancmnt can b controlld by adjusting diffrnt paramtrs (to larn mor about this topic, plas s th whit papr Camra Paramtrs - Maximizing th Imag Quality). In this whit papr, th color-formats cratd by th camra lctronics ar discussd. FirWir Kamras - Spctral snsitivity and color formats

3 CCD chips (monochrom) Th Imaging Sourc uss thr Sony CCD chips for its monochrom FirWir camras. Th spctral diagrams hav bn takn from th manufacturr's data sht. Plas not that th manufacturr dos not spcify dviations to th spcifid valus. Sony ICX98BL: usd by all monochrom FirWir camras from Th Imaging Sourc with a rsolution of 64 x 48 (.g. DMK 21F4, DMK 21AF4, DMK 21BF4,...). Plas also s th tabl Th Imaging Sourc FirWir camras. Snsitivity [%] Sony ICX24AL: usd by all monochrom FirWir camras from Th Imaging Sourc with a rsolution of 124 x 768 (.g. DMK 31AF3, DMK 31BF3,...). Plas also s th tabl Th Imaging Sourc FirWir camras. Snsitivity [%] Wavlngth [nm] Sony ICX25AL: usd by all monochrom FirWir camras from Th Imaging Sourc with a rsolution of 128 x 96 (.g. DMK 41AF2, DMK 41BF2,...). Plas also s th tabl Th Imaging Sourc FirWir camras. Snsitivity [%] Wavlngth [nm] Wavlngth [nm] FirWir Kamras - Spctral snsitivity and color formats

4 CCD chips (color) Th Imaging Sourc uss thr Sony CCD chips for its color FirWir camras. Th spctral diagrams hav bn takn from th manufacturr's data sht. Plas not that th manufacturr dos not spcify dviations to th spcifid valus. Sony ICX98BQ: usd by all color and Bayr FirWir camras from Th Imaging Sourc with a rsolution of 64 x 48 (.g. DFK 21F4, DBK 21F4, DFK 21AF4, DBK 21AF4, DFK 21BF4, DBK 21BF4,...). Plas also s th tabl Th Imaging Sourc FirWir camras. Snsitivity [%] Blu Grn Rd 2 Sony ICX24AK: usd by all color and Bayr FirWir camras from Th Imaging Sourc with a rsolution of 124 x 768 (.g. DFK 31AF3, DBK 31AF3, DFK 31BF3, DBK 31BF3,...). Plas also s th tabl Th Imaging Sourc FirWir camras. Snsitivity [%] Wavlngth [nm] Blu Grn Rd 2 Sony ICX25AK: usd by all color and Bayr FirWir camras from Th Imaging Sourc with a rsolution of 128 x 96 (.g. DFK 41AF2, DBK 41AF2, DFK 41BF2, DBK 41BF2,...). Plas also s th tabl Th Imaging Sourc FirWir camras. Snsitivity[%] Wavlngth [nm] Blu Grn Rd Wavlngth [nm] FirWir Kamras - Spctral snsitivity and color formats

5 Bayr filtr Bayr camras provid th color CCD's "raw contnt" and hnc, at first glanc, a monochrom imag with 8 bit/pixl. Th color information is "hiddn" in th pixl's coordinat: Sinc w know which color is rprsntd by a pixl, th "8 bit" is color information and not a graylvl. Thus, a pixl is mor or lss rd, grn or blu. Ths raw data, howvr, ar not usful for visualization purposs. A pixl nds all thr color valus for good visualization rsults. But sinc th camra only provids on color valu pr pixl, th camra lctronics "stimat" th two missing valus, by intrpolating th nighbor's color valus. Dtails may b studid in th whit papr How Color Camras work. Bayr filtr Camra lctronics Imag of a Bayr camra Imag of a color camra (RGB format) FirWir Kamras - Spctral snsitivity and color formats

6 IR cut filtr In contrast to th human y, CCD chips ar also snsitiv to nar infrard light. In th cas of color camras, this would lad to a prdominanc of rd. An IR cut filtr corrctd this situation. Idally, an IR cut filtr should b compltly transparnt for th visibl part of th spctrum, whil blocking all IR light. Th diagram at th right dpicts th actual bhavior of th IR cut filtr usd in Th Imaging Sourc FirWir camras. Plas not: Th Imaging Sourc uss IR cut filtr xclusivly in color camras, but not in monochrom or Bayr camras. Transparncy [%] Wavlngth [nm] 8 9 FirWir Kamras - Spctral snsitivity and color formats

7 Optical low pass filtr (OLPF) Fin and rgular structurs in th objct that is to b acquird may lad to moiré ffcts in th rsulting imag. An OLPF rducs this ffct, but causs blurrd imags. Thrfor Th Imaging Sourc only uss OLPFs in th low-cost color camras DFK 21F4, DFM 21F4 and DFM 21F4-ML (plas also s th tabl Th Imaging Sourc FirWir camras). If thr should b moiré ffcts in th contxt of camras without am OLPF, you may rduc thm by slightly dfocussing th lns. Original imag without moiré ffct Moiré ffct Th OLPF's ffct FirWir Kamras - Spctral snsitivity and color formats

8 Color formats Th camra lctronics nhanc th CCD chips' raw data. This nhancmnt can b controlld by adjusting diffrnt paramtrs (plas s th whit papr Camra Paramtrs - Maximizing th Imag Quality). Additionally, th camra lctronics ar rsponsibl for th color format of th providd imag data. Dpnding upon thir typ, Th Imaging Sourc camras offr diffrnt color formats. Thy ar dfind by th standard protocol DCAM / IIDC (plas s th whit papr What is DCAM / IIDC?). Important: Th format nams usd by th standard DCAM / IIDC ar not usd by th oprating systm. Th nams usd undr Windows ar put in [brackts]: Monochrom camras Th Imaging Sourc monochrom camras us th format Y8 (Mono) [quivalnt to Y8]. This format provids 256 graylvls pr pixl. Color camras Th Imaging Sourc color camras mainly us th format YUV 4:2:2 [quivalnt to UYVY]. This format provids 256 graylvls (Y) for vry pixl and altrnating 256 color valus (U) and 256 color valus (V) for vry othr pixl. Th low-cost color camras DFK 21F4, DFM 21F4 and DFM 21F4-ML additionally offr th format YUV 4:1:1 [quivalnt to Y411]. Bayr camras Th Imaging Sourc Bayr camras us th format Y8 (Mono) [quivalnt to Y8] and thus, at first glanc, sm to bhav as a monochrom camra. But as sn in th sction Bayr filtr, th color information is "hiddn" in th pixls coordinats. Th drivrs that ar shippd by Th Imaging Sourc for ths camras crat th propritary format [BY8], in addition to th format [Y8]. This nw format adviss subsqunt programs that it is th [Y8] format of a Bayr camra. FirWir Kamras - Spctral snsitivity and color formats

9 Th Imaging Sourc FirWir camras Th following tabl givs you an ovrviw of th faturs of diffrnt Th Imaging Sourc FirWir camras (if a camra has mor than on color format, th rcommndd format is bold): Camra Color format fps Int OLPF IR CCD DMK 21F4 Y (Mono) 3 - Sony ICX98BL DFK 21F4 DFK 21F4* YUV 4:1:1 3 3 Y (Mono) 3 3 YUV 4:1:1 3 3 Y (Mono) Sony ICX98BQ Sony ICX98BQ DBK 21F4 Y (Mono) 3 - Sony ICX98BQ DMK 21AF4 Y (Mono) 3 - Sony ICX98BL DFK 21AF4 DBK 21AF4 Y (Mono) 3 - Y (Mono) 3 - Sony ICX98BQ DMK 21BF4 Y (Mono) 3 - Sony ICX98BL DFK 21BF4 DBK 21BF4 Y (Mono) 3 - Y (Mono) 3 - Sony ICX98BQ PTO * : producd as of 7/25 fps : max fram pr scond Int : Color intrpolation OLPF : Optical Low Pass Filt IR : IR cut filtr CCD : Typ of Sony CCD chip FirWir Kamras - Spctral snsitivity and color formats

10 Camra Color format fps Int OLPF IR CCD DMK 31AF3 Y (Mono) 3 - Sony ICX24AL DFK 31AF3 DBK 31AF3 Y (Mono) 3 - Y (Mono) 3 - Sony ICX24AK DMK 31BF3 Y (Mono) 3 - Sony ICX24AL DFK 31BF3 DBK 31BF3 Y (Mono) 3 - Y (Mono) 3 - Sony ICX24AK DMK 41AF2 Y (Mono) 15 - Sony ICX25AL DFK 41AF2 DBK 41AF2 YUV 4:2: Y (Mono) 15 - Y (Mono) 15 - YUV 4:2: Sony ICX25AK DMK 41BF2 Y (Mono) 15 - Sony ICX25AL DFK 41BF2 DBK 41BF2 YUV 4:2: Y (Mono) 15 - Y (Mono) 15 - YUV 4:2: Sony ICX25AK fps : max fram pr scond Int : Color intrpolation OLPF : Optical Low Pass Filt IR : IR cut filtr CCD : Typ of Sony CCD chip FirWir Kamras - Spctral snsitivity and color formats 1