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Added image preprocessing information

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Silver-T 2018-05-25 11:44:59 +10:00
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2 changed files with 47 additions and 5 deletions

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@misc{openData, title={Open Database License (ODbL) v1.0}, url={https://opendatacommons.org/licenses/odbl/1.0/}, journal={Open Data Commons}, year={2018}, month={Feb}}

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\usepackage[justification=centering]{caption} % Used for captions
\captionsetup[figure]{font=small} % Makes captions small
\newcommand\tab[1][0.5cm]{\hspace*{#1}} % Defines a new command to use 'tab' in text
% Math package
\usepackage{amsmath}
\usepackage[comma, numbers]{natbib} % Used for the bibliography
\usepackage{amsmath} % Math package
% Enable that parameters of \cref{}, \ref{}, \cite{}, ... are linked so that a reader can click on the number an jump to the target in the document
\usepackage{hyperref}
%enable \cref{...} and \Cref{...} instead of \ref: Type of reference included in the link
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% Easier compilation
\usepackage{bookmark}
\usepackage{natbib}
\bibliographystyle{ieeetr}
\begin{document}
\title{Waldo discovery using Neural Networks}
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\section{Background}
\section{Methods}
A couple of papers that may be useful:
- LeNet: http://yann.lecun.com/exdb/publis/pdf/lecun-01a.pdf
- AlexNet: http://papers.nips.cc/paper/4824-imagenet-classification-with-deep-convolutional-neural-networks
- General comparison of LeNet and AlexNet:
"On the Performance of GoogLeNet and AlexNet Applied to Sketches", Pedro Ballester and Ricardo Matsumura Araujo
- Deep NN Architecture:
https://www-sciencedirect-com.ezproxy.lib.monash.edu.au/science/article/pii/S0925231216315533
\section{Methods}
\tab
In order to effectively utilize the aforementioned modelling and classification techniques, a key consideration is the data they are acting on.
A dataset containing Waldo and non-Waldo images was obtained from an Open Database\footnote{``The Open Database License (ODbL) is a license agreement intended to allow users to freely share, modify, and use [a] Database while maintaining [the] same freedom for others"\cite{openData}}hosted on the predictive modelling and analytics competition framework, Kaggle.
The distinction between images containing Waldo, and those that do not, was providied by the separation of the images in different sub-directories.
It was therefore necessary to preprocess these images before they could be utilised by the proposed machine learning algorithms.
\subsection{Image Processing}
\tab
The Waldo image database consists of images of size 64$\times$64, 128$\times$128, and 256$\times$256 pixels obtained by dividing complete Where's Waldo? puzzles.
Within each set of images, those containing Waldo are located in a folder called `waldo', and those not containing Waldo, in a folder called `not\_waldo'.
Since Where's Waldo? puzzles are usually densely populated and contain fine details, the 64$\times$64 pixel set of images were selected to train and evaluate the machine learning models.
These images provide the added benefit of containing the most individual images of the three size groups.
\\
\par
Each of the 64$\times$64 pixel images were inserted into a Numpy
\footnote{Numpy is a popular Python programming library for scientific computing}
array of images, and a binary value was inserted into a seperate list at the same index.
These binary values form the labels for each image (waldo or not waldo).
Colour normalisation was performed on each so that artefacts in an image's colour profile correspond to meaningful features of the image (rather than photographic method).
\\
\par
Each original puzzle is broken down into many images, and only contains one Waldo. Although Waldo might span multiple 64$\times$64 pixel squares, this means that the non-Waldo data far outnumbers the Waldo data.
To combat the bias introduced by the skewed data, all Waldo images were artificially augmented by performing random rotations, reflections, and introducing random noise in the image to produce news images.
In this way, each original Waldo image was used to produce an additional 10 variations of the image, inserted into the image array.
This provided more variation in the true positives of the data set and assists in the development of more robust methods by exposing each technique to variations of the image during the training phase.
\\
\par
Despite the additional data, there were still over ten times as many non-Waldo images than Waldo images.
Therefore, it was necessary to cull the no-Waldo data, so that there was an even split of Waldo and non-Waldo images, improving the representation of true positives in the image data set.
\\
\section{Results}
\section{Discussion and Conclusion}
\bibliographystyle{humannat}
\clearpage % Ensures that the references are on a seperate page
\pagebreak
% References
\section{References}
\renewcommand{\refname}{}
\bibliography{references}
\end{document}