Physics of Digital Photography

373 Pages·2020·31.251 MB·English

by  D. A. Rowlands

Physics of Digital Photography
(Second Edition)
IOP Series in Emerging Technologies in Optics and Photonics
Series Editor
R Barry Johnson a Senior Research Professor at Alabama A&M
University, has been involved for over 50 years in lens design,
optical systems design, electro-optical systems engineering, and
photonics. He has been a faculty member at three academic
institutions engaged in optics education and research, employed
by a number of companies, and provided consulting services.
DrJohnsonisanIOPFellow,SPIEFellowandLifeMember,OSAFellow,andwas
the 1987 President of SPIE. He serves on the editorial board of Infrared Physics &
Technology and Advances in Optical Technologies. Dr Johnson has been awarded
manypatents,haspublishednumerouspapersandseveralbooksandbookchapters,
andwasawardedthe2012OSA/SPIEJosephWGoodmanBookWritingAwardfor
LensDesignFundamentals,SecondEdition.Heisaperennialco-chairoftheannual
SPIE Current Developments in Lens Design and Optical Engineering Conference.
Foreword
Untilthe1960s,thefieldofopticswasprimarilyconcentratedintheclassicalareasof
photography, cameras, binoculars, telescopes, spectrometers, colorimeters, radio-
meters,etc.Inthelate1960s,opticsbegantoblossomwiththeadventofnewtypesof
infrareddetectors,liquidcrystaldisplays(LCD),lightemittingdiodes(LED),charge
coupled devices (CCD), lasers, holography, fiber optics, new optical materials,
advances in optical and mechanical fabrication, new optical design programs, and
many more technologies.With thedevelopment ofthe LED,LCD, CCD and other
electo-optical devices, the term ‘photonics’ came into vogue in the 1980s to describe
thescienceofusinglightindevelopmentofnewtechnologiesandtheperformanceof
amyriadofapplications.Today,opticsandphotonicsaretrulypervasivethroughout
societyandnewtechnologiesarecontinuingtoemerge.Theobjectiveofthisseriesis
to provide students, researchers, and those who enjoy self-teaching with a wide-
ranging collection of books that each focus on a relevant topic in technologies and
applicationofopticsand photonics.Thesebookswill provideknowledgetoprepare
thereadertobebetterabletoparticipateintheseexcitingareasnowandinthefuture.
The title of this series is Emerging Technologies in Optics and Photonics where
‘emerging’ is taken to mean ‘coming into existence,’ ‘coming into maturity,’ and
‘coming into prominence.’ IOP Publishing and I hope that you find this Series of
significant value to you and your career.
Physics of Digital Photography
(Second Edition)
D A Rowlands
IOP Publishing, Bristol, UK
ªIOPPublishingLtd2020
Allrightsreserved.Nopartofthispublicationmaybereproduced,storedinaretrievalsystem
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[email protected].
DARowlandshasassertedhisrighttobeidentifiedastheauthorofthisworkinaccordancewith
sections77and78oftheCopyright,DesignsandPatentsAct1988.
ISBN 978-0-7503-2558-5(ebook)
ISBN 978-0-7503-2559-2(print)
ISBN 978-0-7503-2560-8(myPrint)
ISBN 978-0-7503-2561-5(mobi)
DOI 10.1088/978-0-7503-2558-5
Version:20201001
IOPebooks
BritishLibraryCataloguing-in-PublicationData:Acataloguerecordforthisbookisavailable
fromtheBritishLibrary.
PublishedbyIOPPublishing,whollyownedbyTheInstituteofPhysics,London
IOPPublishing,TempleCircus,TempleWay,Bristol,BS16HG,UK
USOffice:IOPPublishing,Inc.,190NorthIndependenceMallWest,Suite601,Philadelphia,
PA19106,USA
For my parents, Ann and Gareth

Contents
Preface xv
Author biography xvi
Abbreviations xvii
1 Photographic optics 1-1
1.1 Optical image formation 1-2
1.1.1 Refraction 1-2
1.1.2 Lens design 1-3
1.1.3 Paraxial imaging 1-4
1.1.4 Gaussian optics 1-6
1.1.5 Compound lenses: ynu raytrace 1-7
1.1.6 Principal planes 1-9
1.1.7 Gaussian conjugate equation 1-11
1.1.8 Thick and thin lenses 1-12
1.1.9 Focal length 1-14
1.1.10Magnification 1-18
1.1.11Lens aberrations 1-19
1.2 Focusing 1-20
1.2.1 Unit focusing 1-21
1.2.2 Internal focusing 1-23
1.2.3 Single lens reflex cameras 1-24
1.2.4 Phase-detect autofocus 1-25
1.3 Framing 1-27
1.3.1 Entrance and exit pupils 1-27
1.3.2 Chief rays 1-28
1.3.3 Pupil magnification 1-30
1.3.4 Angular field of view formula 1-32
1.3.5 Focus breathing 1-35
1.3.6 Focal length multiplier 1-36
1.3.7 Perspective 1-37
1.3.8 Keystone distortion 1-39
1.4 Depth of field 1-40
1.4.1 Circle of confusion 1-40
1.4.2 Depth of field formulae 1-42
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PhysicsofDigitalPhotography(SecondEdition)
1.4.3 Depth of field control 1-44
1.4.4 Hyperfocal distance 1-44
1.4.5 Focus and recompose limits 1-46
1.4.6 Bokeh 1-48
1.5 Photometric exposure 1-51
1.5.1 Photometry 1-51
1.5.2 Flux emitted into a cone 1-53
1.5.3 Relative aperture 1-56
1.5.4 f-number 1-58
1.5.5 Working f-number 1-59
1.5.6 f-stop 1-61
1.5.7 Natural vignetting 1-62
1.5.8 Camera equation 1-64
1.5.9 Shutters 1-65
1.5.10 f-number for aplanatic lenses 1-68
References 1-71
2 Digital output and exposure strategy 2-1
2.1 Raw data 2-2
2.1.1 Sensor response 2-2
2.1.2 Colour 2-3
2.1.3 Dynamic range transfer 2-5
2.2 Digital output levels 2-6
2.2.1 Bit depth reduction 2-7
2.2.2 Posterisation 2-8
2.2.3 Lightness 2-9
2.2.4 Gamma encoding 2-9
2.2.5 Gamma decoding 2-11
2.3 Image dynamic range 2-13
2.3.1 Gamma curves 2-14
2.3.2 Tone curves 2-15
2.3.3 Raw headroom 2-17
2.3.4 Shadow and highlight dynamic range 2-17
2.4 Histograms 2-18
2.4.1 Luminance histograms 2-19
2.4.2 Image histograms 2-19
viii
PhysicsofDigitalPhotography(SecondEdition)
2.5 Average photometry 2-20
2.5.1 Reflected light meter equation 2-21
2.5.2 Proportionality constant 2-22
2.5.3 Photographic constant 2-23
2.5.4 Hand-held meter calibration constant 2-24
2.5.5 Average scene luminance 2-24
2.5.6 Exposure value 2-25
2.6 Exposure index 2-26
2.6.1 ISO speed 2-27
2.6.2 Standard output sensitivity 2-30
2.6.3 Recommended exposure index 2-32
2.6.4 Extended highlights 2-32
2.7 Advanced metering 2-34
2.7.1 Exposure compensation 2-35
2.7.2 In-camera metering modes 2-35
2.7.3 Incident light metering 2-35
2.8 Exposure modes 2-36
2.8.1 Aperture priority 2-36
2.8.2 Shutter priority 2-37
2.8.3 Program mode 2-37
2.8.4 Manual mode 2-38
2.9 Photographic lighting 2-38
2.9.1 Sunrise and sunset 2-40
2.10 Neutral density filters 2-41
2.10.1 Graduated neutral density filters 2-42
2.11 Polarizing filters 2-44
2.11.1 Malus’ law 2-45
2.11.2 Surface reflections 2-46
2.11.3 Blue skies 2-47
2.11.4 Circular polarizing filters 2-48
2.12 High dynamic range 2-49
2.12.1 High dynamic range imaging 2-50
2.12.2 Tone mapping 2-52
2.13 Image display 2-54
2.13.1 Luma 2-54
2.13.2 Display luminance 2-55
2.13.3 Display dynamic range 2-56
References 2-57
ix