Forensic photography plays a vitally important part in the investigation of crime and the subsequent administration of justice. Written by a practitioner with many years professional experience, this book provides an overview of the most common forensic photography techniques in use today for those readers who may not have a detailed understanding of camera techniques and who need to get to grips with the use of light and other key scientific aspects of the job. It covers image capture issues, file handling and relevant equipment, such as lasers and UV lights, and explores how they work.
The predominance of the digital camera has resulted in an increasing trend for police forces across the world to use untrained camera users, rather than expert photographers. Therefore, this book will prove invaluable for those practitioners who need to produce accurate and clear photographic evidence, above and beyond the point and shoot mode on their cameras.
Foreword xi
Preface xiii
Acknowledgements xix
About the Companion Website xxi
1 Image Processing 1
1.1 Introduction 1
1.2 The digital image 2
1.3 Image acquisition 3
1.4 Colour images 4
1.5 The imaging chain and workflow 5
1.6 White balance 7
1.7 Image histogram 8
1.7.1 Levels and grey-picker tools 8
1.8 Image processing terminology 12
1.9 Digital image processing operations 14
1.9.1 Image cropping 14
1.9.2 Image resampling (resizing) 15
1.9.3 Image flipping and rotation 15
1.9.4 Linear scales 17
1.10 Classes of operations 19
1.10.1 Point processing 19
1.10.2 Addition 19
1.10.3 Subtraction 19
1.10.4 Multiplication and division 20
1.10.5 The bad news: artefacts 22
1.10.6 The good news: versatility 22
1.11 Noise reduction 22
1.12 Sharpening filters 24
1.13 History log 27
1.14 Layers 27
1.14.1 Adjustment layers and layer masks 27
1.14.2 Composite images 28
1.15 Bit depth and dynamic range 28
1.16 File formats 29
1.17 Image compression 29
1.18 Image processing at image capture 30
1.19 Properties of common formats 31
1.20 Image archiving and the audit trail 32
1.20.1 Best practice and the audit trail 33
1.21 Printing images 35
1.22 Image storage 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 The shutter 46
2.6 F-stops and apertures 47
2.7 So what is the correct exposure? 49
2.8 Metering modes 50
2.8.1 Measuring the light 50
2.8.2 Camera meters 51
2.8.3 Incident light meters 51
2.9 Getting the right exposure 51
2.10 Dynamic range 52
2.11 Depth of field and focus 53
2.11.1 Lens choice 55
2.11.2 Distance to the subject 56
2.11.3 The rule of thirds 56
2.11.4 Focus 56
2.11.5 Manual focus 58
2.12 Lenses 65
2.12.1 Focal lengths 67
Reference 77
3 The Use of Flash 79
3.1 How does it work? 79
3.2 Guide numbers 81
3.2.1 What is the guide number? 81
3.3 Flash modes 83
3.3.1 Manual mode 83
3.4 The inverse square law (ISL) 90
3.4.1 The ISL (long version) 90
3.4.2 The ISL short version 92
3.4.3 Automatic 92
3.4.4 Through The Lens metered flash (TTL) 93
3.4.5 Other settings 94
3.5 The practical application of flash 95
3.5.1 Flash only 95
3.5.2 Open flash 99
3.5.3 Fill in flash 105
3.6 Types of flash 108
3.6.1 Hammerhead units 108
3.6.2 Ring flash 108
3.6.3 Semi ring flashes 109
3.6.4 Studio flash 110
4 Crime Scene Photography 113
4.1 Overview 113
4.1.1 What are we being asked to photograph? 114
4.1.2 When do I take photographs? 114
4.1.3 How will I take the photographs? 115
4.2 Personal protective equipment (PPE) 115
4.2.1 Stepping plates 118
4.3 The generics of scene photography 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 Photographic equipment 123
4.5 Composition 124
4.5.1 Interiors 130
4.6 Specific types of scenes 134
4.6.1 Motor vehicles 138
4.6.2 Assault victims 145
4.6.3 Prisoners 146
4.6.4 Property 147
4.6.5 Fire damaged scenes 149
4.6.6 RTC (Road Traffic Collisions) 151
4.6.7 Homicides and postmortems (PM) 152
4.7 Appendix 1: Trouble-shooting 159
References 162
5 Light as a Forensic Photographer's Tool 163
5.1 Overview of alternative light sources (ALS) 163
5.2 The Electromagnetic Spectrum (EMS) 164
5.3 Fluorescence 168
5.4 Alternative light sources 174
5.4.1 Ultraviolet (UV) light sources 174
5.4.2 LASERs (Light Amplification by Stimulated Emission of Radiation) 177
5.4.3 Crime-lites 180
5.4.4 Tuneable light sources 181
5.5 Filters 183
5.6 Infrared (IR) 187
5.7 White light 189
5.7.1 White light types 189
5.8 Conclusion 193
References 193
6 The Photography of Injuries 195
6.1 Overview 195
6.2 The nature of injuries 197
6.2.1 Bruises 197
6.2.2 Burns 198
6.2.3 Cuts and abrasions 199
6.2.4 Bites 199
6.3 The photography 200
6.4 Before we start 203
6.5 Techniques and equipment required 204
6.5.1 Camera 204
6.5.2 Illumination 204
6.5.3 Polarising filters 206
6.5.4 Forensic rulers 207
6.6 The colour reference 207
6.6.1 Cross-polarised photography 207
6.7 Reflected Ultraviolet (UV) 213
6.8 Lenses 216
6.9 Lighting 216
6.10 Capturing the image 218
6.10.1 Induced fluorescence 218
6.10.2 Induced fluorescence for cadavers only 221
6.10.3 Infrared (IR) 222
6.10.4 Summary 224
References 228
Further useful reading 229
7 Finger and Shoe Mark Photography 231
7.1 Overview 231
7.2 The nature of finger marks 232
7.3 Shoe marks 236
7.4 Equipment 241
7.5 Lighting techniques 245
7.5.1 Copy lighting 245
7.5.2 Bright field illumination 246
7.5.3 Dark field illumination 247
7.5.4 Oblique lighting 254
7.5.5 Specular or coaxial illumination 255
7.5.6 Photography of specular marks 259
7.5.7 Transillumination or backlighting 261
7.6 Chemically enhanced marks 262
7.6.1 Treated marks on porous surfaces 263
7.6.2 Non porous surfaces 265
7.7 Latent marks 269
7.7.1 Fluorescence 269
7.7.2 Painting with light 275
7.8 Shoe marks 278
7.8.1 Latent dust marks 278
7.8.2 Contaminated marks 279
7.8.3 Physical shoe mark impressions 282
7.8.4 Photography of shoe marks 282
7.9 Tyre marks 284
7.10 Blood enhancement techniques 289
7.10.1 Acid yellow 7 289
7.10.2 Acid violet 17 289
7.10.3 Amido Black (acid black 1) 290
7.10.4 LCV 291
7.10.5 Huffing and dead sets 292
References 295
8 The Proactive Use of Light in Forensic Photography 297
8.1 Overview 297
8.2 The detection of body fluids using an alternative light source 297
8.3 Inks 301
8.4 Sign writing 305
8.5 The detection of blood 307
8.6 Luminol 309
8.7 Other uses of Infrared (IR) 313
8.7.1 Vein patterns 314
8.7.2 Clothing 317
References 322
9 Specialist Equipment and Techniques 325
9.1 Peripheral cameras 325
9.2 Object modelling 332
9.3 Multi-spectral imaging camera 335
9.4 High speed imaging 340
9.5 UVC photography 346
References 354
10 Panoramic (Immersive or 360 ?) and Elevated imaging 355
10.1 Overview 355
10.2 Spheron 357
10.3 Digital Single Lens Reflex 360 ? 358
10.4 Elevated imaging 367
Reference 373
Appendix 1 Tripods and Camera Supports 375
A. 1 Tripods 375
A. 2 Scene tripods 375
A.2. 1 The 058 Triaut Tripod 376
A.2. 2 Manfrotto 055 fitted with the Manfrotto 322RCE head 377
A.2. 3 Benbo 377
A.2. 4 Studio type stands 377
A. 3 Other types of camera platforms 377
A.3. 1 Gorilla pods 377
A.3. 2 Monopods 378
A. 4 Video tripods 379
A. 5 Other types of clamps 379
Index 383
