67 research outputs found
Transformation invariance in hand shape recognition
In hand shape recognition, transformation invariance is key for successful recognition. We propose a system that is invariant to small scale, translation and shape variations. This is achieved by using a-priori knowledge to create a transformation subspace for each hand shape. Transformation subspaces are created by performing principal component analysis (PCA) on images produced using computer animation. A method to increase the efficiency of the system is outlined. This is achieved using a technique of grouping subspaces based on their origin and then organising them into a hierarchical decision tree. We compare the accuracy of this technique with that of the tangent distance technique and display the result
Sample Mixed-Based Data Augmentation for Domestic Audio Tagging
Audio tagging has attracted increasing attention since last decade and has
various potential applications in many fields. The objective of audio tagging
is to predict the labels of an audio clip. Recently deep learning methods have
been applied to audio tagging and have achieved state-of-the-art performance,
which provides a poor generalization ability on new data. However due to the
limited size of audio tagging data such as DCASE data, the trained models tend
to result in overfitting of the network. Previous data augmentation methods
such as pitch shifting, time stretching and adding background noise do not show
much improvement in audio tagging. In this paper, we explore the sample mixed
data augmentation for the domestic audio tagging task, including mixup,
SamplePairing and extrapolation. We apply a convolutional recurrent neural
network (CRNN) with attention module with log-scaled mel spectrum as a baseline
system. In our experiments, we achieve an state-of-the-art of equal error rate
(EER) of 0.10 on DCASE 2016 task4 dataset with mixup approach, outperforming
the baseline system without data augmentation.Comment: submitted to the workshop of Detection and Classification of Acoustic
Scenes and Events 2018 (DCASE 2018), 19-20 November 2018, Surrey, U
Manifold Parzen Windows
The similarity between objects is a fundamental element of many learning algorithms. Most non-parametric methods take this similarity to be fixed, but much recent work has shown the advantages of learning it, in particular to exploit the local invariances in the data or to capture the possibly non-linear manifold on which most of the data lies. We propose a new non-parametric kernel density estimation method which captures the local structure of an underlying manifold through the leading eigenvectors of regularized local covariance matrices. Experiments in density estimation show significant improvements with respect to Parzen density estimators. The density estimators can also be used within Bayes classifiers, yielding classification rates similar to SVMs and much superior to the Parzen classifier. La similarité entre objets est un élément fondamental de plusieurs algorithmes d'apprentissage. La plupart des méthodes non paramétriques supposent cette similarité constante, mais des travaux récents ont montré les avantages de les apprendre, en particulier pour exploiter les invariances locales dans les données ou pour capturer la variété possiblement non linéaire sur laquelle reposent la plupart des données. Nous proposons une nouvelle méthode d'estimation de densité à noyau non paramétrique qui capture la structure locale d'une variété sous-jacente en utilisant les vecteurs propres principaux de matrices de covariance locales régularisées. Les expériences d'estimation de densité montrent une amélioration significative sur les estimateurs de densité de Parzen. Les estimateurs de densité peuvent aussi être utilisés à l'intérieur de classificateurs de Bayes, menant à des taux de classification similaires à ceux des SVMs, et très supérieurs au classificateur de Parzen.density estimation, non-parametric models, manifold models, probabilistic classifiers, estimation de densité, modèles non paramétriques, modèles de variétés, classification probabiliste
Manitest: Are classifiers really invariant?
Invariance to geometric transformations is a highly desirable property of
automatic classifiers in many image recognition tasks. Nevertheless, it is
unclear to which extent state-of-the-art classifiers are invariant to basic
transformations such as rotations and translations. This is mainly due to the
lack of general methods that properly measure such an invariance. In this
paper, we propose a rigorous and systematic approach for quantifying the
invariance to geometric transformations of any classifier. Our key idea is to
cast the problem of assessing a classifier's invariance as the computation of
geodesics along the manifold of transformed images. We propose the Manitest
method, built on the efficient Fast Marching algorithm to compute the
invariance of classifiers. Our new method quantifies in particular the
importance of data augmentation for learning invariance from data, and the
increased invariance of convolutional neural networks with depth. We foresee
that the proposed generic tool for measuring invariance to a large class of
geometric transformations and arbitrary classifiers will have many applications
for evaluating and comparing classifiers based on their invariance, and help
improving the invariance of existing classifiers.Comment: BMVC 201
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