Caldwell, Sabrina
Description
Image manipulation is subverting the credibility of photographs
as a whole. Currently there is no practical solution for
asserting the authenticity of a photograph. People express their
concern about this when asked but continue to operate in a
‘business as usual’ fashion.
While a range of digital forensic technologies has been developed
to address falsification of digital photographs, such
technologies begin with ‘sourceless’ images and conclude with
...[Show more] results in equivocal terms of probability, while not addressing
the meaning and content contained within the image.
It is interesting that there is extensive research into
computer-based image forgery detection, but very little research
into how we as humans perceive, or fail to perceive, these
forgeries when we view them. The survey, eye-gaze tracking
experiments and neural network analysis undertaken in this
research contribute to this limited pool of knowledge.
The research described in this thesis investigates human
perceptions of images that are manipulated and, by comparison,
images that are not manipulated. The data collected, and their
analyses, demonstrate that humans are poor at identifying that an
image has been manipulated. I consider some of the implications
of digital image manipulation, explore current approaches to
image credibility, and present a potential digital image
authentication framework that uses technology and tools that
exploit social factors such as reputation and trust to create a
framework for technologically packaging/wrapping images with
social assertions of authenticity, and surfaced metadata
information.
The thesis is organised into 6 chapters.
Chapter 1: Introduction
I briefly introduce the history of photography, highlighting its
importance as reportage, and discuss how it has changed from its
introduction in the early 19th century to today. I discuss photo
manipulation and consider how it has changed along with
photography. I describe the relevant literature on the subject of
image authentication and the use of eye gaze tracking and neural
nets in identifying the role of human vision in image
manipulation detection, and I describe my area of research within
this context.
Chapter 2: Literature review
I describe the various types of image manipulation, giving
examples, and then canvas the literature to describe the
landscape of image manipulation problems and extant solutions,
namely:
• the nature of image manipulation,
• investigations of human perceptions of image manipulation,
• eye gaze tracking and manipulated images,
• known efforts to create solutions to the problem of
preserving unadulterated photographic representations and the
meanings they hold.
Finally, I position my research activities within the context of
the literature.
Chapter 3: The research
I describe the survey and experiments I undertook to investigate
attitudes toward image manipulation, research human perceptions
of manipulated and unmanipulated images, and to trial elements of
a new wrapper-style file format that I call .msci (mobile
self-contained image), designed to address image authenticity
issues.
Methods, results and discussion for each element are presented in
both explanatory text and by presentation of papers resulting
from the experiments.
Chapter 4: Analysis of eye gaze data using classification neural
networks
I describe pattern classifying neural network analysis applied to
selected data obtained from the experiments and the insights this
analysis provided into the opaque realm of cognitive perception
as seen through the lens of eye gaze.
Chapter 5: Discussion
I synthesise and discuss the outcomes of the survey and
experiments.
I discuss the outcomes of this research, and consider the need
for a distinction between photographs and photo art. I offer a
theoretical formula within which the overall authenticity of an
image can be assessed. In addition I present a potential image
authentication framework built around the .msci file format,
designed in consideration of my investigation of the requirements
of the image manipulation problem space and the experimental work
undertaken in this research.
Chapter 6: Conclusions and future work
This thesis concludes with a summary of the outcomes of my
research, and I consider the need for future experimentation to
expand on the insights gained to date. I also note some ways
forward to develop an image authentication framework to address
the ongoing problem of image authenticity.
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