Detection of second-generation images using an assessment criteria method

DOIhttps://doi.org/10.1108/JCRPP-08-2015-0042
Pages207-222
Published date07 December 2015
Date07 December 2015
AuthorGlenn Porter,Robert Ebeyan
Subject MatterHealth & social care,Criminology & forensic psychology
Detection of second-generation images
using an assessment criteria method
Glenn Porter and Robert Ebeyan
Glenn Porter is Associate
Professor in Photomedia at
the James Cook University,
Queensland, Australia.
Robert Ebeyan is based at
the James Cook University,
Queensland, Australia.
Abstract
Purpose The ability to distinguish between originaland copiedimages has been a persistent forensic
imaging difficulty and can be of some importance to certain criminal and civil investigations. The purpose of
this paper is to introduce a novel assessment criteria method that incorporates visual and metadata-based
information for the purpose of determining whether images are original or second-generation duplicates
(copies made by rephotographing the original hardcopy).
Design/methodology/approach The study reflects difficulties raised from forensic cases and is modelled
on fraud investigation that involved images sourced from camera phones. The method involved a new
assessment-based criteria approach and the results were evaluated through their application to a sample set
of second-generation images.
Findings The evaluation confirmed the validity of several theorised detection artefacts resulting in the
articulation and presentation of 17 detection criteria considered useful for supporting image analysis.
Originality/value The result of this study is an expansion of the tools available to examiners for addressing
complex image authentication problems. The criteria approach also assists with transparently
communicating the details of the photo interpretation processes for review and scrutiny.
Keywords Assessment criteria, Digital imaging, Forensic photography, Forensic science,
Photographic reproduction, Second-generation images
Paper type Research paper
Introduction
The ability to authenticate visual evidence, in particular, distinguish between original and
duplicate images made by rephotographing the original can be of value to forensic investigations
(Bestagini et al., 2013; Thongkamwitoon et al., 2015; Yin and Fang, 2012). In the context of this
paper, the ability to detect second-generation images can be of particular relevance to areas
such as insurance fraud investigation where the originality of an image may hold legal significance
or assist shape investigative efforts. This paper explores an approach for the detection of
second-generation images using a novel assessment criteria method.
Originalimages are produced whenlight, reflected or emitted from theobjects of the world around
us is transformed into a two-dimensional photographic representation. Second-generation images
may be photographs made by rephotographing pre-existing original images. Their capture can
occur at different locations and under dissimilar photographic conditions than that of the original.
Yin and Fang (2012) describe rephotographing as a special case of creating imagesdue to both
the subject and product of the photographic process consisting of images (Figure 1). The term
second-generation imageis fundamentally synonymous with notions presented in the literature
concerning photographic copying,recapturing,rephotographingor photographic
reproductionof existing photographs.
Received 31 August 2015
Revised 12 October 2015
Accepted 12 October 2015
DOI 10.1108/JCRPP-08-2015-0042 VOL. 1 NO. 4 2015, pp.207-222, © Emerald Group Publishing Limited, ISSN 2056-3841
j
JOURNAL OF CRIMINOLOGICAL RESEARCH, POLICY AND PRACTICE
j
PAGE207
Second-generation images examined in this paper are those produced from rephotographing
existing hardcopy photographic prints with a digital camera system comprising of lens, shutter
assembly, image sensor and electronic subsystem (Salvaggio, 2009). Image outputs from other
devices such as photocopying and scanning systems were not investigated as part of this study.
Currently, the task of detecting second-generation images remains challenging. Standardised
methods have yet to be formalised and adopted within the wider forensic imaging discipline.
At the time of this paper, a limited number of methods have been presented in the literature for
the detection of rephotographed imagery. Current publications focus on the algorithmic-based
detection of second-generation images from sources such as LCD screens (Bestagini et al.,
2013; Cao and Kot, 2010; Thongkamwitoon et al., 2015) and rephotographed hardcopy prints
(Gao et al., 2010; Yin and Fang, 2012; Yu et al., 2008). The underlying commonality among
existing second-generation image detection methods is their foundation in computational-based
image analysis.
This paper aims to expand th e knowledge and tools avail able for the detection o f
second-generation images through the introduction of an approach that, dissimilar to existing
techniques, does not have a fundamental dependence on computational analysis for the
detection of second-generation photographic reproductions from hardcopy prints. This work
introduces the new forensic investigation concept of using an assessment criteriamethod. The
assessment criteria relies on human-based visual analysis and informed judgement to assess the
value of detected artefacts inherent in rephotographed images.
The need to determine whetherphotographic evidence consists of originals or second-generation
images has been seen in recent insurance fraud investigations. Insurance companies processing
claims may require proof of ownership of insured items, which can often be satisfied through
Figure 1 Diagram illustrating production pathways for first or originaland
second-generation digital images
Real Life Scene (e.g. buildings)
First gen. image pathway
Capture
Output
First Generation Image
Capture
Capture
Second gen. image pathway
Output
Digital Camera Device Second Generation Image
Key:
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