Forensic Photography A Practitioner's Guide

417 Pages·2014·61.042 MB·English

by  Nick Marsh

FORENSIC
PHOTOGRAPHY
A PRACTITIONER’S GUIDE
Nick Marsh

Forensic Photography

Forensic Photography
A Practitioner’s Guide
Nick Marsh
Consultant Forensic Practitioner, UK
Thiseditionfirstpublished2014 C⃝2014byJohnWiley&Sons,Ltd
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1 2014
Contents
Foreword xi
Preface xiii
Acknowledgements xix
About the Companion Website xxi
1 Image Processing 1
1.1 Introduction 1
1.2 Thedigitalimage 2
1.3 Imageacquisition 3
1.4 Colourimages 4
1.5 Theimagingchainandworkflow 5
1.6 Whitebalance 7
1.7 Imagehistogram 8
1.7.1 Levelsandgrey-pickertools 8
1.8 Imageprocessingterminology 12
1.9 Digitalimageprocessingoperations 14
1.9.1 Imagecropping 14
1.9.2 Imageresampling(resizing) 15
1.9.3 Imageflippingandrotation 15
1.9.4 Linearscales 17
1.10 Classesofoperations 19
1.10.1 Pointprocessing 19
1.10.2 Addition 19
1.10.3 Subtraction 19
1.10.4 Multiplicationanddivision 20
1.10.5 Thebadnews:artefacts 22
1.10.6 Thegoodnews:versatility 22
1.11 Noisereduction 22
1.12 Sharpeningfilters 24
1.13 Historylog 27
vi CONTENTS
1.14 Layers 27
1.14.1 Adjustmentlayersandlayermasks 27
1.14.2 Compositeimages 28
1.15 Bitdepthanddynamicrange 28
1.16 Fileformats 29
1.17 Imagecompression 29
1.18 Imageprocessingatimagecapture 30
1.19 Propertiesofcommonformats 31
1.20 Imagearchivingandtheaudittrail 32
1.20.1 Bestpracticeandtheaudittrail 33
1.21 Printingimages 35
1.22 Imagestorage 35
1.23 Summary 35
2 Cameras and Lenses 37
2.1 Overview 37
2.2 Cameras 40
2.3 Exposure 43
2.4 ISOs 45
2.5 Theshutter 46
2.6 F-stopsandapertures 47
2.7 Sowhatisthecorrectexposure? 49
2.8 Meteringmodes 50
2.8.1 Measuringthelight 50
2.8.2 Camerameters 51
2.8.3 Incidentlightmeters 51
2.9 Gettingtherightexposure 51
2.10 Dynamicrange 52
2.11 Depthoffieldandfocus 53
2.11.1 Lenschoice 55
2.11.2 Distancetothesubject 56
2.11.3 Theruleofthirds 56
2.11.4 Focus 56
2.11.5 Manualfocus 58
2.12 Lenses 65
2.12.1 Focallengths 67
Reference 77
3 The Use of Flash 79
3.1 Howdoesitwork? 79
3.2 Guidenumbers 81
3.2.1 Whatistheguidenumber? 81
3.3 Flashmodes 83
3.3.1 Manualmode 83
3.4 Theinversesquarelaw(ISL) 90
3.4.1 TheISL(longversion) 90
CONTENTS vii
3.4.2 TheISLshortversion 92
3.4.3 Automatic 92
3.4.4 ThroughTheLensmeteredflash(TTL) 93
3.4.5 Othersettings 94
3.5 Thepracticalapplicationofflash 95
3.5.1 Flashonly 95
3.5.2 Openflash 99
3.5.3 Fillinflash 105
3.6 Typesofflash 108
3.6.1 Hammerheadunits 108
3.6.2 Ringflash 108
3.6.3 Semiringflashes 109
3.6.4 Studioflash 110
4 Crime Scene Photography 113
4.1 Overview 113
4.1.1 Whatarewebeingaskedtophotograph? 114
4.1.2 WhendoItakephotographs? 114
4.1.3 HowwillItakethephotographs? 115
4.2 Personalprotectiveequipment(PPE) 115
4.2.1 Steppingplates 118
4.3 Thegenericsofscenephotography 119
4.3.1 Sunshine 119
4.3.2 Rain 121
4.3.3 Wind 121
4.3.4 Fog 122
4.3.5 Snow 122
4.3.6 Cold 122
4.4 Photographicequipment 123
4.5 Composition 124
4.5.1 Interiors 130
4.6 Specifictypesofscenes 134
4.6.1 Motorvehicles 138
4.6.2 Assaultvictims 145
4.6.3 Prisoners 146
4.6.4 Property 147
4.6.5 Firedamagedscenes 149
4.6.6 RTC(RoadTrafficCollisions) 151
4.6.7 Homicidesandpostmortems(PM) 152
4.7 Appendix1:Trouble-shooting 159
References 162
5 Light as a Forensic Photographer’s Tool 163
5.1 Overviewofalternativelightsources(ALS) 163
5.2 TheElectromagneticSpectrum(EMS) 164
5.3 Fluorescence 168
viii CONTENTS
5.4 Alternativelightsources 174
5.4.1 Ultraviolet(UV)lightsources 174
5.4.2 LASERs(LightAmplificationbyStimulatedEmission
ofRadiation) 177
5.4.3 Crime-lites 180
5.4.4 Tuneablelightsources 181
5.5 Filters 183
5.6 Infrared(IR) 187
5.7 Whitelight 189
5.7.1 Whitelighttypes 189
5.8 Conclusion 193
References 193
6 The Photography of Injuries 195
6.1 Overview 195
6.2 Thenatureofinjuries 197
6.2.1 Bruises 197
6.2.2 Burns 198
6.2.3 Cutsandabrasions 199
6.2.4 Bites 199
6.3 Thephotography 200
6.4 Beforewestart 203
6.5 Techniquesandequipmentrequired 204
6.5.1 Camera 204
6.5.2 Illumination 204
6.5.3 Polarisingfilters 206
6.5.4 Forensicrulers 207
6.6 Thecolourreference 207
6.6.1 Cross-polarisedphotography 207
6.7 ReflectedUltraviolet(UV) 213
6.8 Lenses 216
6.9 Lighting 216
6.10 Capturingtheimage 218
6.10.1 Inducedfluorescence 218
6.10.2 Inducedfluorescenceforcadaversonly 221
6.10.3 Infrared(IR) 222
6.10.4 Summary 224
References 228
Furtherusefulreading 229
7 Finger and Shoe Mark Photography 231
7.1 Overview 231
7.2 Thenatureoffingermarks 232
7.3 Shoemarks 236
7.4 Equipment 241