Search Results for author: Robert Sabourin

Found 45 papers, 9 papers with code

Local overlap reduction procedure for dynamic ensemble selection

1 code implementation16 Jun 2022 Mariana A. Souza, Robert Sabourin, George D. C. Cavalcanti, Rafael M. O. Cruz

Class imbalance is a characteristic known for making learning more challenging for classification models as they may end up biased towards the majority class.

Dynamic Ensemble Selection Using Fuzzy Hyperboxes

2 code implementations20 May 2022 Reza Davtalab, Rafael M. O. Cruz, Robert Sabourin

Most dynamic ensemble selection (DES) methods utilize the K-Nearest Neighbors (KNN) algorithm to estimate the competence of classifiers in a small region surrounding the query sample.

Classifier Pool Generation based on a Two-level Diversity Approach

no code implementations3 Nov 2020 Marcos Monteiro, Alceu S. Britto Jr, Jean P. Barddal, Luiz S. Oliveira, Robert Sabourin

This paper describes a classifier pool generation method guided by the diversity estimated on the data complexity and classifier decisions.

Vocal Bursts Valence Prediction

A Comprehensive Comparison of End-to-End Approaches for Handwritten Digit String Recognition

no code implementations29 Oct 2020 Andre G. Hochuli, Alceu S. Britto Jr, David A. Saji, Jose M. Saavedra, Robert Sabourin, Luiz S. Oliveira

Over the last decades, most approaches proposed for handwritten digit string recognition (HDSR) have resorted to digit segmentation, which is dominated by heuristics, thereby imposing substantial constraints on the final performance.

object-detection Object Detection +1

An Investigation of Feature Selection and Transfer Learning for Writer-Independent Offline Handwritten Signature Verification

no code implementations19 Oct 2020 Victor L. F. Souza, Adriano L. I. Oliveira, Rafael M. O. Cruz, Robert Sabourin

We proposed a method based on a global validation strategy with an external archive to control overfitting during the search for the most discriminant representation.

feature selection Playing the Game of 2048 +1

Intrapersonal Parameter Optimization for Offline Handwritten Signature Augmentation

no code implementations13 Oct 2020 Teruo M. Maruyama, Luiz S. Oliveira, Alceu S. Britto Jr, Robert Sabourin

The method is used to generate offline signatures in the image and the feature space and train an ASVS.

Random Forest for Dissimilarity-based Multi-view Learning

no code implementations16 Jul 2020 Simon Bernard, Hongliu Cao, Robert Sabourin, Laurent Heutte

Many classification problems are naturally multi-view in the sense their data are described through multiple heterogeneous descriptions.

MULTI-VIEW LEARNING

A Novel Random Forest Dissimilarity Measure for Multi-View Learning

no code implementations6 Jul 2020 Hongliu Cao, Simon Bernard, Robert Sabourin, Laurent Heutte

Its main challenge is most often to exploit the complementarities between these representations to help solve a classification/regression task.

Metric Learning MULTI-VIEW LEARNING

Improving BPSO-based feature selection applied to offline WI handwritten signature verification through overfitting control

no code implementations7 Apr 2020 Victor L. F. Souza, Adriano L. I. Oliveira, Rafael M. O. Cruz, Robert Sabourin

This paper investigates the presence of overfitting when using Binary Particle Swarm Optimization (BPSO) to perform the feature selection in a context of Handwritten Signature Verification (HSV).

feature selection Playing the Game of 2048

A white-box analysis on the writer-independent dichotomy transformation applied to offline handwritten signature verification

no code implementations3 Apr 2020 Victor L. F. Souza, Adriano L. I. Oliveira, Rafael M. O. Cruz, Robert Sabourin

Among the advantages of this framework is its scalability to deal with some of these challenges and its ease in managing new writers, and hence of being used in a transfer learning context.

Transfer Learning

Multi-label learning for dynamic model type recommendation

1 code implementation1 Apr 2020 Mariana A. Souza, Robert Sabourin, George D. C. Cavalcanti, Rafael M. O. Cruz

Our proposed framework builds a multi-label meta-classifier responsible for recommending a set of relevant model types based on the local data complexity of the region surrounding each test sample.

Multi-Label Learning Recommendation Systems +1

An End-to-End Approach for Recognition of Modern and Historical Handwritten Numeral Strings

no code implementations28 Mar 2020 Andre G. Hochuli, Alceu S. Britto Jr., Jean P. Barddal, Luiz E. S. Oliveira, Robert Sabourin

An end-to-end solution for handwritten numeral string recognition is proposed, in which the numeral string is considered as composed of objects automatically detected and recognized by a YoLo-based model.

Segmentation

Meta-learning for fast classifier adaptation to new users of Signature Verification systems

1 code implementation17 Oct 2019 Luiz G. Hafemann, Robert Sabourin, Luiz S. Oliveira

This is particularly challenging for skilled forgeries, where a forger practices imitating the user's signature, and often is able to create forgeries visually close to the original signatures.

Meta-Learning

Characterizing and evaluating adversarial examples for Offline Handwritten Signature Verification

2 code implementations10 Jan 2019 Luiz G. Hafemann, Robert Sabourin, Luiz S. Oliveira

The phenomenon of Adversarial Examples is attracting increasing interest from the Machine Learning community, due to its significant impact to the security of Machine Learning systems.

BIG-bench Machine Learning Object Recognition

Decoupling Direction and Norm for Efficient Gradient-Based L2 Adversarial Attacks and Defenses

5 code implementations23 Nov 2018 Jérôme Rony, Luiz G. Hafemann, Luiz S. Oliveira, Ismail Ben Ayed, Robert Sabourin, Eric Granger

Research on adversarial examples in computer vision tasks has shown that small, often imperceptible changes to an image can induce misclassification, which has security implications for a wide range of image processing systems.

ICPRAI 2018 SI: On dynamic ensemble selection and data preprocessing for multi-class imbalance learning

no code implementations22 Nov 2018 Rafael M. O. Cruz, Mariana A. Souza, Robert Sabourin, George D. C. Cavalcanti

Hence, this paper presents an empirical analysis of dynamic selection techniques and data preprocessing methods for dealing with multi-class imbalanced problems.

General Classification

META-DES.Oracle: Meta-learning and feature selection for ensemble selection

no code implementations1 Nov 2018 Rafael M. O. Cruz, Robert Sabourin, George D. C. Cavalcanti

The key issue in Dynamic Ensemble Selection (DES) is defining a suitable criterion for calculating the classifiers' competence.

feature selection General Classification +1

Analyzing different prototype selection techniques for dynamic classifier and ensemble selection

no code implementations1 Nov 2018 Rafael M. O. Cruz, Robert Sabourin, George D. C. Cavalcanti

The more important step in DES techniques is estimating the competence of the base classifiers for the classification of each specific test sample.

Classification General Classification +1

On Meta-Learning for Dynamic Ensemble Selection

no code implementations1 Nov 2018 Rafael M. O. Cruz, Robert Sabourin, George D. C. Cavalcanti

The meta-features are computed using the training data and used to train a meta-classifier that is able to predict whether or not a base classifier from the pool is competent enough to classify an input instance.

Meta-Learning

FIRE-DES++: Enhanced Online Pruning of Base Classifiers for Dynamic Ensemble Selection

no code implementations1 Oct 2018 Rafael M. O. Cruz, Dayvid V. R. Oliveira, George D. C. Cavalcanti, Robert Sabourin

Despite being very effective in several classification tasks, Dynamic Ensemble Selection (DES) techniques can select classifiers that classify all samples in the region of competence as being from the same class.

Classification General Classification

META-DES: A Dynamic Ensemble Selection Framework using Meta-Learning

no code implementations30 Sep 2018 Rafael M. O. Cruz, Robert Sabourin, George D. C. Cavalcanti, Tsang Ing Ren

The meta-features are extracted from the training data and used to train a meta-classifier to predict whether or not a base classifier is competent enough to classify an input instance.

General Classification Meta-Learning

Online local pool generation for dynamic classifier selection: an extended version

no code implementations5 Sep 2018 Mariana A. Souza, George D. C. Cavalcanti, Rafael M. O. Cruz, Robert Sabourin

Thus, we propose in this work an online pool generation method that produces a locally accurate pool for test samples in difficult regions of the feature space.

General Classification

A writer-independent approach for offline signature verification using deep convolutional neural networks features

no code implementations26 Jul 2018 Victor L. F. Souza, Adriano L. I. Oliveira, Robert Sabourin

The use of features extracted using a deep convolutional neural network (CNN) combined with a writer-dependent (WD) SVM classifier resulted in significant improvement in performance of handwritten signature verification (HSV) when compared to the previous state-of-the-art methods.

Dynamic voting in multi-view learning for radiomics applications

no code implementations20 Jun 2018 Hongliu Cao, Simon Bernard, Laurent Heutte, Robert Sabourin

Cancer diagnosis and treatment often require a personalized analysis for each patient nowadays, due to the heterogeneity among the different types of tumor and among patients.

MULTI-VIEW LEARNING

Segmentation-Free Approaches for Handwritten Numeral String Recognition

no code implementations24 Apr 2018 Andre G. Hochuli, Luiz E. S. Oliveira, Alceu S. Britto Jr, Robert Sabourin

This paper presents segmentation-free strategies for the recognition of handwritten numeral strings of unknown length.

Segmentation

Dynamic Ensemble Selection VS K-NN: why and when Dynamic Selection obtains higher classification performance?

no code implementations21 Apr 2018 Rafael M. O. Cruz, Hiba H. Zakane, Robert Sabourin, George D. C. Cavalcanti

Experiments are performed on 18 state-of-the-art DS techniques over 30 classification datasets and results show that DS methods present a significant boost in classification accuracy even though they use the same neighborhood as the K-NN.

Classification General Classification

An Ensemble Generation Method Based on Instance Hardness

no code implementations20 Apr 2018 Felipe N. Walmsley, George D. C. Cavalcanti, Dayvid V. R. Oliveira, Rafael M. O. Cruz, Robert Sabourin

Techniques such as Bagging and Boosting have been successfully applied to a variety of problems.

K-Nearest Oracles Borderline Dynamic Classifier Ensemble Selection

no code implementations18 Apr 2018 Dayvid V. R. Oliveira, George D. C. Cavalcanti, Thyago N. Porpino, Rafael M. O. Cruz, Robert Sabourin

The K-Nearest Oracles Eliminate (KNORA-E) DES selects all classifiers that correctly classify all samples in the region of competence of the test sample, if such classifier exists, otherwise, it removes from the region of competence the sample that is furthest from the test sample, and the process repeats.

Fixed-sized representation learning from Offline Handwritten Signatures of different sizes

1 code implementation2 Apr 2018 Luiz G. Hafemann, Robert Sabourin, Luiz S. Oliveira

Methods for learning feature representations for Offline Handwritten Signature Verification have been successfully proposed in recent literature, using Deep Convolutional Neural Networks to learn representations from signature pixels.

Representation Learning

Improve the performance of transfer learning without fine-tuning using dissimilarity-based multi-view learning for breast cancer histology images

no code implementations29 Mar 2018 Hongliu Cao, Simon Bernard, Laurent Heutte, Robert Sabourin

In the context of ICIAR 2018 Grand Challenge on Breast Cancer Histology Images, we compare one handcrafted feature extractor and five transfer learning feature extractors based on deep learning.

MULTI-VIEW LEARNING Transfer Learning

Dissimilarity-based representation for radiomics applications

no code implementations12 Mar 2018 Hongliu Cao, Simon Bernard, Laurent Heutte, Robert Sabourin

Radiomics is a term which refers to the analysis of the large amount of quantitative tumor features extracted from medical images to find useful predictive, diagnostic or prognostic information.

feature selection MULTI-VIEW LEARNING

On dynamic ensemble selection and data preprocessing for multi-class imbalance learning

no code implementations11 Mar 2018 Rafael M. O. Cruz, Robert Sabourin, George D. C. Cavalcanti

Hence, this paper presents an empirical analysis of dynamic selection techniques and data preprocessing methods for dealing with multi-class imbalanced problems.

General Classification

Deep Learning Architectures for Face Recognition in Video Surveillance

no code implementations27 Feb 2018 Saman Bashbaghi, Eric Granger, Robert Sabourin, Mostafa Parchami

In video-based FR systems, facial models of target individuals are designed a priori during enrollment using a limited number of reference still images or video data.

Face Recognition

DESlib: A Dynamic ensemble selection library in Python

2 code implementations14 Feb 2018 Rafael M. O. Cruz, Luiz G. Hafemann, Robert Sabourin, George D. C. Cavalcanti

DESlib is an open-source python library providing the implementation of several dynamic selection techniques.

Learning Features for Offline Handwritten Signature Verification using Deep Convolutional Neural Networks

4 code implementations16 May 2017 Luiz G. Hafemann, Robert Sabourin, Luiz S. Oliveira

Verifying the identity of a person using handwritten signatures is challenging in the presence of skilled forgeries, where a forger has access to a person's signature and deliberately attempt to imitate it.

Analyzing features learned for Offline Signature Verification using Deep CNNs

no code implementations15 Jul 2016 Luiz G. Hafemann, Robert Sabourin, Luiz S. Oliveira

Research on Offline Handwritten Signature Verification explored a large variety of handcrafted feature extractors, ranging from graphology, texture descriptors to interest points.

Bayesian Hyperparameter Optimization for Ensemble Learning

no code implementations20 May 2016 Julien-Charles Lévesque, Christian Gagné, Robert Sabourin

Our method consists in building a fixed-size ensemble, optimizing the configuration of one classifier of the ensemble at each iteration of the hyperparameter optimization algorithm, taking into consideration the interaction with the other models when evaluating potential performances.

Bayesian Optimization Ensemble Learning +1

Writer-independent Feature Learning for Offline Signature Verification using Deep Convolutional Neural Networks

no code implementations4 Apr 2016 Luiz G. Hafemann, Robert Sabourin, Luiz S. Oliveira

Automatic Offline Handwritten Signature Verification has been researched over the last few decades from several perspectives, using insights from graphology, computer vision, signal processing, among others.

A DEEP analysis of the META-DES framework for dynamic selection of ensemble of classifiers

no code implementations2 Sep 2015 Rafael M. O. Cruz, Robert Sabourin, George D. C. Cavalcanti

In order to perform a more robust ensemble selection, we proposed the META-DES framework using meta-learning, where multiple criteria are encoded as meta-features and are passed down to a meta-classifier that is trained to estimate the competence level of a given classifier.

Meta-Learning

Offline Handwritten Signature Verification - Literature Review

no code implementations28 Jul 2015 Luiz G. Hafemann, Robert Sabourin, Luiz S. Oliveira

The area of Handwritten Signature Verification has been broadly researched in the last decades, but remains an open research problem.

Evaluation of Genotypic Diversity Measurements Exploited in Real-Coded Representation

no code implementations1 Jul 2015 Guillaume Corriveau, Raynald Guilbault, Antoine Tahan, Robert Sabourin

Numerous genotypic diversity measures (GDMs) are available in the literature to assess the convergence status of an evolutionary algorithm (EA) or describe its search behavior.

Offline Signature-Based Fuzzy Vault (OSFV: Review and New Results

no code implementations18 Aug 2014 George S. Eskander, Robert Sabourin, Eric Granger

An offline signature-based fuzzy vault (OSFV) is a bio-cryptographic implementation that uses handwritten signature images as biometrics instead of traditional passwords to secure private cryptographic keys.

A Classifier-free Ensemble Selection Method based on Data Diversity in Random Subspaces

no code implementations13 Aug 2014 Albert H. R. Ko, Robert Sabourin, Alceu S. Britto Jr, Luiz E. S. Oliveira

Our scheme is the first ensemble selection method to be presented in the literature based on the concept of data diversity.

Clustering

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