Can Digital Photography replace the Visual Assessment of Bruise Age?

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The final report on my Photographic Science degree major project. While the practical work didn't go so well the research is pretty extensive and written with the intention that it covered both the medical and photographic aspects in a way that could be understood by each.Thought it may be useful in anyone happens to be hunting the web for research on a similar project on what would create a very useful forensic tool.

Text of Can Digital Photography replace the Visual Assessment of Bruise Age?

Can Digital Photography replace the Visual Assessment of Bruise Age?

Martin R. Perrett B.Sc. in Photography & Digital Imaging University of Westminster August 2009

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Martin R. Perrett BSc Photographic Science and Digital Imaging

Table of Contentsi.

Abstract..............................................

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ii. Hypothesis.......................................... iii. Abbreviations...................................... iv. Acknowledgements............................

v. Introduction.........................................1. The Role of Bruising in Forensic Science

1.1 What is a Bruise................................ 1.2 The Science of Bruising................... 1.3 The Appearance of a Bruise............. 1.4 The biochemistry of bruising and its repair 1.5 Visual assessment of a bruise......... 2. The Science of Colour............................ 2.1 Light................................................... 2.2 The human visual system................ 2.3 Colour Perception and Appearance 2.4 The inadequacies the human visual system................................................ 2.5 Basics of Colour Reproduction....... 2.6 Metamerism....................................... 2.7 Colour matching and the CIE colorimetry system............................................... 2.8 Colour Spaces and Colour Management

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Measuring the colour of bruises..3.1 Spectrophotometry........................... 3.2 Colourimetry using tristimulus Colourimetry..................................... 3.3 Colourimetry using digital cameras

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Aims & Objectives..........................................

Martin R. Perrett BSc Photographic Science and Digital Imaging

4. Methods....................................................... 4.1 Apparatus.............................................. 4.2 Software................................................ 4.3 Bruise creation..................................... 4.4. Image Capture..................................... 4.5 Measuring the Colour Chart................ 4.6 Pre-processing..................................... 4.7 Processing................................................... 4.8 Characterization Error......................... 5. Experimental and results........................... 5.1 Bruising.................................................. 5.2 Illumination............................................ 5.3 Colour Chart Measurements................ 5.4 Bruise changes with time..................... 5.5 Characterisation and Error................... 6. Discussion.................................................. 7. Conclusions................................................ References.................................................. Appendices............................................... 1. Colour Chart......................................... 2. Calibrating the Spectrophotometer... 3. Colour chart and greyscale Readings 4. Reproducibility data............................. 5. Bruise infliction times.......................... 6. Camera Settings................................... 7. Times and dates of photographs of bruise BL 8. Times and dates of photographs of bruise BU 9. Times and dates of photographs of bruise ML 10. Times and dates of photographs of bruise MR 11. Function for the extraction of data from grey scale and colour chart.....................

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Martin R. Perrett BSc Photographic Science and Digital Imaging

N.B. All images are in public domain unless otherwise stated. Images are reproduced as .jpg and printed on a colour laser printer. High quality images of results are provided on the DVD that accompanies.

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Martin R. Perrett BSc Photographic Science and Digital Imaging

i. AbstractIt is well known that bruises change in colour as they dissipate over time. The biological processes that return the skin to its regular state are well understood and known to be the cause of this colour change. There seems to have been a general acceptance in the medical and forensic communities that the age of a bruise can be determined by the inspection of different colours present in the bruise. Estimation of the age of a bruise is usually preformed by forensic experts whose observations can have legal consequences. This view has come in to question in recent publications1 and also proven to be unreliable in two recent undergraduate studies2,3 performed at Barts Hospital Medical School. However the correlated results of a number of papers documenting the changing colour of bruises over their duration do suggest that there is a trend4 from this the simple conclusion is made that a more quantitative analysis of the colours in bruises is required in order to gain any conclusive evidence that bruise colour relates directly to age. ii. Hypothesis It is possible to extract useful colour information from digital images of bruises taken with consumer digital cameras. The analyses of such information could lead to an effective and scientifically valid method to accurately determine the age of a bruise for forensic purposes.

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Martin R. Perrett BSc Photographic Science and Digital Imaging

iii. Abbreviations A & E = Accident and Emergency (English equivalent of an Emergency Room) CR2 dpi cm CIE = Canon Raw version 2 (file extension .CR2) = dots per inch = centimetre, 10-2 m = Commission Internationale de l'Eclairage - the International Commission on Illumination CRT = Cathode Ray Tube CVD = Colour vision deficiency DVD = Digital Versatile Disc EXIF- = Exchangeable image file format FME = Forensic Medical Examiner GUI ICC ISO = Graphical User Interface = International Colour Consortium = International Standard Organisation (referring to ISO 5800:1987 the standard for measuring the speed of colour negative film) JPEG = Joint photographic experts group (file extension .jpg) K LCD nm PC = Kelvin = Liquid Crystal Display = nanometre, 10-9 m = Personal Computer

CCD = Charge- coupled Device

RGB = Red, Green and Blue colour space SPD = Spectral Power Distribution sRGB = standard Red, Green and Blue colour space TIFF = Tagged Image File Format (file extension .tif) USB = Universal Serial Bus

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Martin R. Perrett BSc Photographic Science and Digital Imaging

iv. Acknowledgements First would to thank all Margaret Pilling and Sophie Grossman whose projects where the starting point. Secondly I would like to thank my farther Prof. David Perrett for introducing me to the work of Pilling and Grossman and his help in me understanding the biochemical side of this study and his guidance in the writing of the final project report. I would also like to thank all my course staff for their guidance and support, John Smith, Dr. Efthimia Bilissi, Elizabeth Allen and Dr. Sophie Triantaphillidou. Lastly I would like to thank the subjects who took part.

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Martin R. Perrett BSc Photographic Science and Digital Imaging

v. Introduction In his most recent review Langlois5 asked whether there was any science behind the quest to determine the age of bruises. The aim of this dissertation taken in conjunction with the studies of Pilling2 and Grossman3 is to try and apply a scientific approach to Langlois question. Since Pilling and Grossman were both critical of the abilities of forensic medical examiners to visually age bruises with any accuracy, this research has to been to try and develop a reliable methodology using digital cameras. It is necessary to link research into the medical, forensic and biochemical science of bruises with knowledge of photographic and colour reproduction techniques in order to develop my approach.

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Martin R. Perrett BSc Photographic Science and Digital Imaging

1. The Role of Bruising in Forensic Science1.1. What is a Bruise?Everyone will have seen a bruise and more than likely suffered one. A bruise is formed following a trauma, such as a bump, that does not break the skin but damages the underlying blood vessels. Its appearance is due to the release of blood into the skin or subcutaneous tissues6,7.

Figure 1.1: Types of bruises .The left hand image caused by an accident (photo by M.R. Perrett), right hand image caused as a result of physical violence (courtesy of Prof. P Vanezis).

1.2 The Science of BruisingA bruise, also called a contusion, is defined as bleeding beneath intact skin and it must not be confused with a bleed caused by other events, such as venepuncture or at the site of an injection. Bruises are most commonly caused by blunt force trauma but can also be caused by pressure changes. The trauma in most cases will be accidental from both known and unknown causes. Accidents can range from a simple un-noticed bump to a very serious injury due to say a car crash. Bruises can also result from high contact sports such as rugby, martial arts and boxing. Other causes of bruising are following many hospital operations and some types of dental treatment. Some diseases, e.g. haemophilia, and certain drugs, e.g. aspirin, can cause subcutaneous bleeding which can cause bruises to appear without an injury having occurred.

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Martin R. Perrett BSc Photographic Science and Digital Imaging

Bruises often result from physical violence associated with criminal violence, assault and abuse. Knowing the age of the bruise can be important evidence in confirming whether or not a bruise resulted from such an attack. Currently it is the role of a forensic medical examiner (FME) to estimate the age of the bruise(s) with their professional opinion being used as evidence. Details such as the location of the bruise and time and date of inspection of t