Mercurial > ift6266
changeset 392:5f8fffd7347f
possible image for illustrating perturbations
author | Yoshua Bengio <bengioy@iro.umontreal.ca> |
---|---|
date | Tue, 27 Apr 2010 09:56:18 -0400 |
parents | d76c85ba12d6 |
children | 4c840798d290 |
files | writeup/images/example_t.png writeup/ml.bib writeup/techreport.tex |
diffstat | 3 files changed, 68 insertions(+), 4 deletions(-) [+] |
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--- a/writeup/ml.bib Tue Apr 27 08:55:30 2010 -0400 +++ b/writeup/ml.bib Tue Apr 27 09:56:18 2010 -0400 @@ -2420,7 +2420,9 @@ title = "Learning Deep Architectures for {AI}", journal = {Foundations \& Trends in Mach. Learn.}, year = "2009", - volume = {to appear}, + volume = 2, + number = 1, + pages = {1--127}, } @TechReport{Bengio-TR1312-small,
--- a/writeup/techreport.tex Tue Apr 27 08:55:30 2010 -0400 +++ b/writeup/techreport.tex Tue Apr 27 09:56:18 2010 -0400 @@ -12,11 +12,64 @@ \maketitle \begin{abstract} - +Recent theoretical and empirical work in statistical machine learning has +demonstrated the importance of learning algorithms for deep +architectures, i.e., function classes obtained by composing multiple +non-linear transformations. In the area of handwriting recognition, +deep learning algorithms +had been evaluated on rather small datasets with a few tens of thousands +of examples. Here we propose a powerful generator of variations +of examples for character images based on a pipeline of stochastic +transformations that include not only the usual affine transformations +but also the addition of slant, local elastic deformations, changes +in thickness, background images, color, contrast, occlusion, and +various types of pixel and spatially correlated noise. +We evaluate a deep learning algorithm (Stacked Denoising Autoencoders) +on the task of learning to classify digits and letters transformed +with this pipeline, using the hundreds of millions of generated examples +and testing on the full NIST test set. +We find that the SDA outperforms its +shallow counterpart, an ordinary Multi-Layer Perceptron, +and that it is better able to take advantage of the additional +generated data. \end{abstract} \section{Introduction} +Deep Learning has emerged as a promising new area of research in +statistical machine learning (see~\emcite{Bengio-2009} for a review). +Learning algorithms for deep architectures are centered on the learning +of useful representations of data, which are better suited to the task at hand. +This is in great part inspired by observations of the mammalian visual cortex, +which consists of a chain of processing elements, each of which is associated with a +different representation. In fact, +it was found recently that the features learnt in deep architectures resemble +those observed in the first two of these stages (in areas V1 and V2 +of visual cortex)~\cite{HonglakL2008}. +Processing images typically involves transforming the raw pixel data into +new {\bf representations} that can be used for analysis or classification. +For example, a principal component analysis representation linearly projects +the input image into a lower-dimensional feature space. +Why learn a representation? Current practice in the computer vision +literature converts the raw pixels into a hand-crafted representation +(e.g.\ SIFT features~\cite{Lowe04}), but deep learning algorithms +tend to discover similar features in their first few +levels~\cite{HonglakL2008,ranzato-08,Koray-08,VincentPLarochelleH2008-very-small}. +Learning increases the +ease and practicality of developing representations that are at once +tailored to specific tasks, yet are able to borrow statistical strength +from other related tasks (e.g., modeling different kinds of objects). Finally, learning the +feature representation can lead to higher-level (more abstract, more +general) features that are more robust to unanticipated sources of +variance extant in real data. + +Whereas a deep architecture can in principle be more powerful than a shallow +one in terms of representation, depth appears to render the training problem +more difficult in terms of optimization and local minima. +It is also only recently that +successful algorithms were proposed to overcome some of these +difficulties. + \section{Perturbation and Transformation of Character Images} \subsection{Affine Transformations} @@ -60,7 +113,16 @@ \section{Experimental Results} -\subsection{SDAE vs MLP} +\subsection{SDA vs MLP} + +\begin{center} +\begin{tabular}{lcc} + & train w/ & train w/ \\ + & NIST & P07 + NIST \\ \hline +SDA & & \\ \hline +MLP & & \\ \hline +\end{tabular} +\end{center} \subsection{Perturbed Training Data More Helpful for SDAE} @@ -68,7 +130,7 @@ \section{Conclusions} -\bibliography{strings,ml} +\bibliography{strings,ml,aigaion} \bibliographystyle{mlapa} \end{document} \ No newline at end of file