EvoFIT: A Holistic, Evolutionary Facial Imaging System

This thesis details the development and evaluation of a new photofitting approach. The motivation for this work is that current photofit systems used by the police - whether manual or computerized - do not appear to work very well. Part of the problem with these approaches is they involve a single facial representation that necessitates a verbal interaction. When a multiple presentation is considered, our innate ability to recognize faces is capitalized (and the potentially disruptive effect of the verbal component is reduced). The approach works by employing Genetic Algorithms to evolve a small group of faces to be more like a desired target. The main evolutionary influence is via user input that specifies the similarity of the presented images with the target under construction. The thesis follows three main phases of development. The first involves a simple system modelling the internal components of a face (eyes, eyebrows, nose and mouth) containing features in a fixed relationship with each other. The second phase applies external facial features (hair and ears) along with an appropriate head shape and changes in the relationship between features. That the underlying model is based on Principal Components Analysis captures the statistics of how faces vary in terms of shading, shape and the relationship between features. Modelling was carried out in this way to create more realistic looking photofits and to guard against implausible featural relationships possible with traditional approaches. The encouraging results of these two sections prompted the development of a full photofit system: EvoFIT. This software is shown to have continued promise both in the lab and in a real case. Future work is directed particularly at resolving issues concerning the anonymity of the database faces and the creation of photofits from the subject's memory of a target

Accuracy of relational and featural information in facial-composite images

Facial-composite images are crucial in helping to bring perpetrators to justice and thereby maintain national and international security. Psychology can assist in identifying the accuracy of such facial information as well as ways to improve their identification rates. The current experiment demonstrates that composites tend to differ in terms of their accuracy of featural information (individual facial features) and relational information (spacing between those facial features) depending on the type of composite software used. Composites constructed with feature systems tend to have more-accurate feature information, whilst those constructed with holistic systems tend to have more-accurate relational information. Further, it was found that not only the addition of sunglasses on poor-quality composites, but also viewing composites from the side, can increase their identifiability. This could be applied by the police to potentially increase identification and arrest rates of perpetrators

Towards a comprehensive 3D dynamic facial expression database

Human faces play an important role in everyday life, including the expression of person identity, emotion and intentionality, along with a range of biological functions. The human face has also become the subject of considerable research effort, and there has been a shift towards understanding it using stimuli of increasingly more realistic formats. In the current work, we outline progress made in the production of a database of facial expressions in arguably the most realistic format, 3D dynamic. A suitable architecture for capturing such 3D dynamic image sequences is described and then used to record seven expressions (fear, disgust, anger, happiness, surprise, sadness and pain) by 10 actors at 3 levels of intensity (mild, normal and extreme). We also present details of a psychological experiment that was used to formally evaluate the accuracy of the expressions in a 2D dynamic format. The result is an initial, validated database for researchers and practitioners. The goal is to scale up the work with more actors and expression types

Eyewitnesses and the use and application of cognitive theory

Witnesses and victims may contain the only record of a crime and so their evidence can be invaluable to a criminal investigation. This chapter reviews the different types of evidence provided by these eyewitnesses. The initial focus is on their ability to describe details of a crime and those involved, plus interviewing techniques that attempt to maximise this information recall. Next, the procedures used for identifying offenders are examined. In the final part, face construction systems are discussed along with modern methods for improving their effectiveness

Facial Recall and Computer Composites

Imagine, if you will, that you are sitting quietly outside a café sipping your favourite hot beverage when someone rushes past and snatches your mobile phone, which you left on the table, as you often do. You were able to get a good look at the person’s face, albeit for a short time. Your next hour is spent speaking with a police officer giving a description of what happened and what the offender looked like. It is likely that you could describe accurately what happened. You will probably also be able to describe the perpetrator’s build and clothing. There should be no trouble in saying what was the sex of the person and his or her ethnicity; you should be reasonably accurate at estimating the age, height and weight. You could probably remember some details of the person’s face. Incidents such as these are known as “volume” crime. They occur frequently, often without physical assault to the victim, and their seriousness, at least from a legal perspective, is fairly minor. Due to limitations in police resources, many perpetrators of volume crime are never caught, although time spent locating particularly prolific offenders can be worthwhile. Crimes involving these repeat offenders, and other crimes of a more serious nature including murder, arson and rape, are generally given higher priority in police investigations. It is in these cases that eyewitnesses (witnesses or victims) may be asked to engage in a range of tasks to assist in the detection and later conviction of the offender. When the police have a suspect, they may be asked to take part in an identification parade. (Further details about this are the focus of a separate chapter.) Alternatively, eyewitnesses may be shown photographs of previously arrested criminals for identification, sometimes referred to as mugshots. In the absence of a suspect, CCTV footage or other evidence, witnesses may be called upon to externalise an offender’s face. The aim is to create a visual image based on remembered information, so that it can be shown to other people for identification. Such images are known as facial composites and are seen in the newspapers and on TV, for example, BBC CrimeWatch. The idea is that someone who is familiar with the face will name it to the police and, in doing so, will provide new lines of enquiry. The focus of the current chapter is on the construction and the recognition of facial composites produced by modern software systems. A separate chapter in this volume details how composites are created by sketch artists. This chapter describes and evaluates typical software programs that the police use to construct faces. It will be demonstrated that the traditional approach used with eyewitnesses is generally ineffective for producing identifiable images, and that alternatives are required if composites are to be effective in the battle against crime. Several successful developments are described. The final section looks to the future and asks what might be on the horizon for producing even more effective faces

Cross-age effects on forensic face construction

The own-age bias (OAB) refers to recognition memory being more accurate for people of our own age than other age groups (e.g., Wright and Stroud, 2002). This paper investigated whether the OAB effect is present during construction of human faces (also known as facial composites, often for forensic/police use). In doing so, it adds to our understanding of factors influencing both facial memory across the life span as well as performance of facial composites. Participant-witnesses were grouped into younger (19–35 years) and older (51–80 years) adults, and constructed a single composite from memory of an own- or cross-age target face using the feature-based composite system PRO-fit. They also completed the shortened version of the glasgow face matching test (GFMT; Burton et al., 2010). A separate group of participants who were familiar with the relevant identities attempted to name the resulting composites. Correct naming of the composites revealed the presence of an OAB for older adults, who constructed more identifiable composites of own-age than cross-age faces. For younger adults, age of target face did not influence correct naming and their composites were named at the same level as those constructed by older adults for younger targets. Also, there was no reliable correlation between face perception ability and composite quality. Overall, correct naming was fairly good across the experiment, and indicated benefit for older witnesses for older targets. Results are discussed in terms of contemporary theories of OAB, and implications of the work for forensic practice

Catching More Offenders with EvoFIT Facial Composites: Lab Research and Police Field Trials

Often the only evidence of an offender s identity comes from the memory of an eyewitness For over 12 years we have been developing software called EvoFIT to help eyewitnesses recover their memories of offenders faces to assist police investigations EvoFIT requires eyewitnesses to repeatedly select from arrays of faces with breeding to evolve a face Recently police forces have been formally evaluating EvoFIT in criminal cases The current paper describes four such police audits It is reported that EvoFIT composites directly led to an arrest in 25 4 of cases overall the arrest rate was 38 5 for forces that used a newer less detailed face-recall interview These results are similar to those found in the laboratory using simulated procedures Here we also evaluate the impact of interviewing techniques and outline further work that has improved system performanc

The benefit of context for facial-composite construction

Purpose - The aim of this study was to investigate whether the presence of a whole-face context during facial composite production facilitates construction of facial composite images. Design/Methodology - In Experiment 1, constructors viewed a celebrity face and then developed a facial composite using PRO-fit software in one of two conditions: either the full-face was visible while facial features were selected, or only the feature currently being selected. The composites were named by different participants. We then replicated the study using a more forensically-valid procedure: In Experiment 2 non-football fans viewed an image of a premiership footballer and 24 hours later constructed a composite of the face with a trained software operator. The resulting composites were named by football fans. Findings - In both studies, the presence of the facial context promoted more identifiable facial composites. Research limitations/implications - Current composite software was deployed in a conventional and unconventional way to demonstrate the importance of facial context. Practical implications - Results confirm that composite software should have the whole-face context visible to witnesses throughout construction. Although some software systems do this, there remain others that present features in isolation and these findings show that these systems are unlikely to be optimal. Originality/value - This is the first study to demonstrate the importance of a full-face context for the construction of facial composite images. Results are valuable to police forces and developers of composite software

Forensic procedures for facial-composite construction

Purpose – The paper provides a detailed description of standard procedures for constructing facial composites. These procedures are relevant to forensic practice and are contained in the technical papers of this special issue; the purpose of this paper is also to provide an expanding reference of procedures for future research on facial composites and facial-composite systems. Design/methodology/approach – A detailed account is given of the interaction between practitioner and witness for producing a facial composite. This account involves an overview of the Cognitive Interview (CI) and the Holistic CI (H-CI) techniques used to obtain a description of the face of an offender (target); the authors then describe how this information is used to produce a composite from five popular face-production systems: Sketch, PRO-fit, Electronic Facial Identification Technique (E-FIT), EvoFIT and EFIT-V. An online annex is also made available to provide procedural information for additional composite systems. Practical implications – The work is valuable to forensic practitioners and researchers as a reference for interviewing techniques (involving a CI or an H-CI) and using facial-composite systems. Originality/value – The authors provide an accessible, current guide for how to administer interviewing techniques and how to construct composites from a range of face-production systems

Taking research to members of the public

In 2006, with funding from the Engineering and Physical Sciences Research Council (£30k), we built a themed exhibit with the Sensation Science Centre in Dundee. In the main part of the exhibit, which was kitted out as a ‘police station’, a visitor would see a video of a man pretending to commit a crime and construct a composite of his face using a simplified version of our EvoFIT facial-composite system. Visitors were asked, using written and spoken prompts, to select faces from an array of alternatives, with selected items being ‘bred’ together, to allow a composite to be ‘evolved’. The exhibit then presented a picture of the man’s face alongside the evolved composite, example composites created by previous visitors and an average (‘morphed’) composite from the last four visitors. The exhibit took about five minutes for a user to complete and was accompanied by a ‘Research Lab’, a station which explained more of the underlying science: themes around evolution, computer-based generation of faces, forensic use of composites, etc. We expected the exhibit to last five years but, partly due to the robustness of the hardware, it remains today and is still popular