Search Results for author: Alexandros Iosifidis

Found 143 papers, 50 papers with code

Geometric Deep Learning for Computer-Aided Design: A Survey

no code implementations27 Feb 2024 Negar Heidari, Alexandros Iosifidis

Geometric Deep Learning techniques have become a transformative force in the field of Computer-Aided Design (CAD), and have the potential to revolutionize how designers and engineers approach and enhance the design process.

Dynamic Semantic Compression for CNN Inference in Multi-access Edge Computing: A Graph Reinforcement Learning-based Autoencoder

no code implementations19 Jan 2024 Nan Li, Alexandros Iosifidis, Qi Zhang

To effectively trade-off communication, computation, and inference accuracy, we design a reward function and formulate the offloading problem of CNN inference as a maximization problem with the goal of maximizing the average inference accuracy and throughput over the long term.

Decision Making Edge-computing +1

Improving Unimodal Inference with Multimodal Transformers

no code implementations16 Nov 2023 Kateryna Chumachenko, Alexandros Iosifidis, Moncef Gabbouj

Interestingly, we also observe that optimization of the unimodal branches improves the multimodal branch, compared to a similar multimodal model trained from scratch.

Emotion Recognition Hand Gesture Recognition +2

On Pixel-level Performance Assessment in Anomaly Detection

no code implementations25 Oct 2023 Mehdi Rafiei, Toby P. Breckon, Alexandros Iosifidis

Anomaly detection methods have demonstrated remarkable success across various applications.

Anomaly Detection

Variational Inference for GARCH-family Models

no code implementations5 Oct 2023 Martin Magris, Alexandros Iosifidis

The Bayesian estimation of GARCH-family models has been typically addressed through Monte Carlo sampling.

Bayesian Inference Econometrics +1

Cryptocurrency Portfolio Optimization by Neural Networks

no code implementations2 Oct 2023 Quoc Minh Nguyen, Dat Thanh Tran, Juho Kanniainen, Alexandros Iosifidis, Moncef Gabbouj

Many cryptocurrency brokers nowadays offer a variety of derivative assets that allow traders to perform hedging or speculation.

Portfolio Optimization

Curiosity-Driven Reinforcement Learning based Low-Level Flight Control

1 code implementation28 Jul 2023 Amir Ramezani Dooraki, Alexandros Iosifidis

Curiosity is one of the main motives in many of the natural creatures with measurable levels of intelligence for exploration and, as a result, more efficient learning.

reinforcement-learning

On Feature Diversity in Energy-based Models

no code implementations ICLR Workshop EBM 2021 Firas Laakom, Jenni Raitoharju, Alexandros Iosifidis, Moncef Gabbouj

Energy-based learning is a powerful learning paradigm that encapsulates various discriminative and generative approaches.

Generalization Bounds regression

Audio-Visual Dataset and Method for Anomaly Detection in Traffic Videos

1 code implementation24 May 2023 Błażej Leporowski, Arian Bakhtiarnia, Nicole Bonnici, Adrian Muscat, Luca Zanella, Yiming Wang, Alexandros Iosifidis

We introduce the first audio-visual dataset for traffic anomaly detection taken from real-world scenes, called MAVAD, with a diverse range of weather and illumination conditions.

Anomaly Detection

Accurate Gigapixel Crowd Counting by Iterative Zooming and Refinement

no code implementations16 May 2023 Arian Bakhtiarnia, Qi Zhang, Alexandros Iosifidis

The increasing prevalence of gigapixel resolutions has presented new challenges for crowd counting.

Crowd Counting

Class-Specific Variational Auto-Encoder for Content-Based Image Retrieval

no code implementations23 Apr 2023 Mehdi Rafiei, Alexandros Iosifidis

Using a discriminative representation obtained by supervised deep learning methods showed promising results on diverse Content-Based Image Retrieval (CBIR) problems.

Content-Based Image Retrieval Retrieval

Online Non-Destructive Moisture Content Estimation of Filter Media During Drying Using Artificial Neural Networks

no code implementations27 Mar 2023 Christian Remi Wewer, Alexandros Iosifidis

Moisture content (MC) estimation is important in the manufacturing process of drying bulky filter media products as it is the prerequisite for drying optimization.

Variational Voxel Pseudo Image Tracking

2 code implementations12 Feb 2023 Illia Oleksiienko, Paraskevi Nousi, Nikolaos Passalis, Anastasios Tefas, Alexandros Iosifidis

Uncertainty estimation is an important task for critical problems, such as robotics and autonomous driving, because it allows creating statistically better perception models and signaling the model's certainty in its predictions to the decision method or a human supervisor.

3D Single Object Tracking Autonomous Driving +1

Uncertainty-Aware AB3DMOT by Variational 3D Object Detection

2 code implementations12 Feb 2023 Illia Oleksiienko, Alexandros Iosifidis

Autonomous driving needs to rely on high-quality 3D object detection to ensure safe navigation in the world.

3D Object Detection 3D Object Tracking +3

Adaptive Parameterization of Deep Learning Models for Federated Learning

no code implementations6 Feb 2023 Morten From Elvebakken, Alexandros Iosifidis, Lukas Esterle

While this addresses limitations related to distributed data, it incurs a communication overhead as the model parameters or gradients need to be exchanged regularly during training.

Federated Learning

PromptMix: Text-to-image diffusion models enhance the performance of lightweight networks

no code implementations30 Jan 2023 Arian Bakhtiarnia, Qi Zhang, Alexandros Iosifidis

In this paper, we introduce PromptMix, a method for artificially boosting the size of existing datasets, that can be used to improve the performance of lightweight networks.

Crowd Counting Data Augmentation +2

WLD-Reg: A Data-dependent Within-layer Diversity Regularizer

no code implementations3 Jan 2023 Firas Laakom, Jenni Raitoharju, Alexandros Iosifidis, Moncef Gabbouj

At each optimization step, neurons at a given layer receive feedback from neurons belonging to higher layers of the hierarchy.

Semantic Communication Enabling Robust Edge Intelligence for Time-Critical IoT Applications

no code implementations24 Nov 2022 Andrea Cavagna, Nan Li, Alexandros Iosifidis, Qi Zhang

The proposed Edge Intelligence framework consists of the proposed effectiveness encoding and effectiveness decoding.

Image Augmentation

Attention-based Feature Compression for CNN Inference Offloading in Edge Computing

no code implementations24 Nov 2022 Nan Li, Alexandros Iosifidis, Qi Zhang

We design a feature compression module based on the channel attention method in CNN, to compress the intermediate data by selecting the most important features.

Edge-computing Feature Compression

Design and Prototyping Distributed CNN Inference Acceleration in Edge Computing

no code implementations24 Nov 2022 Zhongtian Dong, Nan Li, Alexandros Iosifidis, Qi Zhang

It is shown that the model selection with distributed inference HALP can significantly improve service reliability compared to the conventional stand-alone computation.

Distributed Computing Edge-computing +2

Structured Pruning Adapters

1 code implementation17 Nov 2022 Lukas Hedegaard, Aman Alok, Juby Jose, Alexandros Iosifidis

To improve on this, we propose Structured Pruning Adapters (SPAs), a family of compressing, task-switching network adapters, that accelerate and specialize networks using tiny parameter sets and structured pruning.

Single Particle Analysis

Computer Vision on X-ray Data in Industrial Production and Security Applications: A Comprehensive Survey

no code implementations10 Nov 2022 Mehdi Rafiei, Jenni Raitoharju, Alexandros Iosifidis

X-ray imaging technology has been used for decades in clinical tasks to reveal the internal condition of different organs, and in recent years, it has become more common in other areas such as industry, security, and geography.

Anomaly Detection

Recognition of Defective Mineral Wool Using Pruned ResNet Models

no code implementations1 Nov 2022 Mehdi Rafiei, Dat Thanh Tran, Alexandros Iosifidis

Considering the low quantity of the dataset, cross-validation and augmentation methods are used during the training.

Manifold Gaussian Variational Bayes on the Precision Matrix

1 code implementation26 Oct 2022 Martin Magris, Mostafa Shabani, Alexandros Iosifidis

We propose an optimization algorithm for Variational Inference (VI) in complex models.

Variational Inference

Graph Reinforcement Learning-based CNN Inference Offloading in Dynamic Edge Computing

no code implementations24 Oct 2022 Nan Li, Alexandros Iosifidis, Qi Zhang

To solve the maximization problem, we propose a graph reinforcement learning-based early-exit mechanism (GRLE), which outperforms the state-of-the-art work, deep reinforcement learning-based online offloading (DROO) and its enhanced method, DROO with early-exit mechanism (DROOE), under different dynamic scenarios.

Decision Making Edge-computing +2

Learning Diversified Feature Representations for Facial Expression Recognition in the Wild

no code implementations17 Oct 2022 Negar Heidari, Alexandros Iosifidis

Diversity of the features extracted by deep neural networks is important for enhancing the model generalization ability and accordingly its performance in different learning tasks.

Facial Expression Recognition Facial Expression Recognition (FER)

Layer Ensembles

2 code implementations10 Oct 2022 Illia Oleksiienko, Alexandros Iosifidis

Deep Ensembles, as a type of Bayesian Neural Networks, can be used to estimate uncertainty on the prediction of multiple neural networks by collecting votes from each network and computing the difference in those predictions.

Efficient CNN with uncorrelated Bag of Features pooling

no code implementations22 Sep 2022 Firas Laakom, Jenni Raitoharju, Alexandros Iosifidis, Moncef Gabbouj

In this paper, we propose an approach that builds on top of BoF pooling to boost its efficiency by ensuring that the items of the learned dictionary are non-redundant.

Crowd Counting on Heavily Compressed Images with Curriculum Pre-Training

no code implementations15 Aug 2022 Arian Bakhtiarnia, Qi Zhang, Alexandros Iosifidis

JPEG image compression algorithm is a widely used technique for image size reduction in edge and cloud computing settings.

Cloud Computing Crowd Counting +1

HyperTime: Implicit Neural Representation for Time Series

no code implementations11 Aug 2022 Elizabeth Fons, Alejandro Sztrajman, Yousef El-Laham, Alexandros Iosifidis, Svitlana Vyetrenko

We show how these networks can be leveraged for the imputation of time series, with applications on both univariate and multivariate data.

Data Augmentation Imputation +2

Efficient High-Resolution Deep Learning: A Survey

no code implementations26 Jul 2022 Arian Bakhtiarnia, Qi Zhang, Alexandros Iosifidis

Cameras in modern devices such as smartphones, satellites and medical equipment are capable of capturing very high resolution images and videos.

Vocal Bursts Intensity Prediction

Augmented Bilinear Network for Incremental Multi-Stock Time-Series Classification

no code implementations23 Jul 2022 Mostafa Shabani, Dat Thanh Tran, Juho Kanniainen, Alexandros Iosifidis

In addition, as the market evolves through time, it is necessary to update the existing models or train new ones when new data is made available.

Classification Time Series +2

Receptive Field-based Segmentation for Distributed CNN Inference Acceleration in Collaborative Edge Computing

no code implementations22 Jul 2022 Nan Li, Alexandros Iosifidis, Qi Zhang

To reduce the computation time and communication overhead, we propose a novel collaborative edge computing using fused-layer parallelization to partition a CNN model into multiple blocks of convolutional layers.

Edge-computing

Distributed Deep Learning Inference Acceleration using Seamless Collaboration in Edge Computing

no code implementations22 Jul 2022 Nan Li, Alexandros Iosifidis, Qi Zhang

This paper studies inference acceleration using distributed convolutional neural networks (CNNs) in collaborative edge computing.

Edge-computing

Analysis of the Effect of Low-Overhead Lossy Image Compression on the Performance of Visual Crowd Counting for Smart City Applications

1 code implementation20 Jul 2022 Arian Bakhtiarnia, Błażej Leporowski, Lukas Esterle, Alexandros Iosifidis

Images and video frames captured by cameras placed throughout smart cities are often transmitted over the network to a server to be processed by deep neural networks for various tasks.

Crowd Counting Image Compression

Variational Neural Networks

3 code implementations4 Jul 2022 Illia Oleksiienko, Dat Thanh Tran, Alexandros Iosifidis

Bayesian Neural Networks (BNNs) provide a tool to estimate the uncertainty of a neural network by considering a distribution over weights and sampling different models for each input.

VPIT: Real-time Embedded Single Object 3D Tracking Using Voxel Pseudo Images

2 code implementations6 Jun 2022 Illia Oleksiienko, Paraskevi Nousi, Nikolaos Passalis, Anastasios Tefas, Alexandros Iosifidis

In this paper, we propose a novel voxel-based 3D single object tracking (3D SOT) method called Voxel Pseudo Image Tracking (VPIT).

3D Single Object Tracking Object +1

Dynamic Split Computing for Efficient Deep Edge Intelligence

no code implementations23 May 2022 Arian Bakhtiarnia, Nemanja Milošević, Qi Zhang, Dragana Bajović, Alexandros Iosifidis

Split computing is a paradigm where a DNN is split into two sections; the first section is executed on the end device, and the output is transmitted to the edge server where the final section is executed.

Edge-computing Hyperparameter Optimization

Quasi Black-Box Variational Inference with Natural Gradients for Bayesian Learning

no code implementations23 May 2022 Martin Magris, Mostafa Shabani, Alexandros Iosifidis

Our Quasi Black-box Variational Inference (QBVI) framework is readily applicable to a wide class of Bayesian inference problems and is of simple implementation as the updates of the variational posterior do not involve gradients with respect to the model parameters, nor the prescription of the Fisher information matrix.

Bayesian Inference Variational Inference

Generalized Reference Kernel for One-class Classification

1 code implementation1 May 2022 Jenni Raitoharju, Alexandros Iosifidis

Focusing on small-scale one-class classification, our analysis and experimental results show that the new formulation provides approaches to regularize, adjust the rank, and incorporate additional information into the kernel itself, leading to improved one-class classification accuracy.

Classification One-Class Classification

Continual Inference: A Library for Efficient Online Inference with Deep Neural Networks in PyTorch

1 code implementation7 Apr 2022 Lukas Hedegaard, Alexandros Iosifidis

We present Continual Inference, a Python library for implementing Continual Inference Networks (CINs) in PyTorch, a class of Neural Networks designed specifically for efficient inference in both online and batch processing scenarios.

Automatic Image Content Extraction: Operationalizing Machine Learning in Humanistic Photographic Studies of Large Visual Archives

no code implementations5 Apr 2022 Anssi Männistö, Mert Seker, Alexandros Iosifidis, Jenni Raitoharju

Applying machine learning tools to digitized image archives has a potential to revolutionize quantitative research of visual studies in humanities and social sciences.

BIG-bench Machine Learning

Continual Spatio-Temporal Graph Convolutional Networks

1 code implementation21 Mar 2022 Lukas Hedegaard, Negar Heidari, Alexandros Iosifidis

Graph-based reasoning over skeleton data has emerged as a promising approach for human action recognition.

Action Recognition Skeleton Based Action Recognition +2

Forecasting large-scale circulation regimes using deformable convolutional neural networks and global spatiotemporal climate data

no code implementations10 Feb 2022 Andreas Holm Nielsen, Alexandros Iosifidis, Henrik Karstoft

Classifying the state of the atmosphere into a finite number of large-scale circulation regimes is a popular way of investigating teleconnections, the predictability of severe weather events, and climate change.

Attribute BIG-bench Machine Learning +1

Non-Linear Spectral Dimensionality Reduction Under Uncertainty

no code implementations9 Feb 2022 Firas Laakom, Jenni Raitoharju, Nikolaos Passalis, Alexandros Iosifidis, Moncef Gabbouj

In this paper, we consider the problem of non-linear dimensionality reduction under uncertainty, both from a theoretical and algorithmic perspectives.

Dimensionality Reduction

Reducing Redundancy in the Bottleneck Representation of the Autoencoders

no code implementations9 Feb 2022 Firas Laakom, Jenni Raitoharju, Alexandros Iosifidis, Moncef Gabbouj

We tested our approach across different tasks: dimensionality reduction using three different dataset, image compression using the MNIST dataset, and image denoising using fashion MNIST.

Dimensionality Reduction Image Compression +1

Self-Attention Neural Bag-of-Features

no code implementations26 Jan 2022 Kateryna Chumachenko, Alexandros Iosifidis, Moncef Gabbouj

In this work, we propose several attention formulations for multivariate sequence data.

Self-attention fusion for audiovisual emotion recognition with incomplete data

1 code implementation26 Jan 2022 Kateryna Chumachenko, Alexandros Iosifidis, Moncef Gabbouj

In this paper, we consider the problem of multimodal data analysis with a use case of audiovisual emotion recognition.

Facial Emotion Recognition

Continual Transformers: Redundancy-Free Attention for Online Inference

1 code implementation17 Jan 2022 Lukas Hedegaard, Arian Bakhtiarnia, Alexandros Iosifidis

Transformers in their common form are inherently limited to operate on whole token sequences rather than on one token at a time.

Audio Classification Online Action Detection +2

Fighting Money Laundering with Statistics and Machine Learning

no code implementations11 Jan 2022 Rasmus Jensen, Alexandros Iosifidis

On the other hand, suspicious behavior flagging is characterized by non-disclosed features and hand-crafted risk indices.

BIG-bench Machine Learning Fairness +1

Learning to ignore: rethinking attention in CNNs

1 code implementation10 Nov 2021 Firas Laakom, Kateryna Chumachenko, Jenni Raitoharju, Alexandros Iosifidis, Moncef Gabbouj

Based on this idea, we propose to reformulate the attention mechanism in CNNs to learn to ignore instead of learning to attend.

Robust channel-wise illumination estimation

1 code implementation10 Nov 2021 Firas Laakom, Jenni Raitoharju, Jarno Nikkanen, Alexandros Iosifidis, Moncef Gabbouj

We test this approach on the proposed method and show that it can indeed be used to avoid several extreme error cases and, thus, improves the practicality of the proposed technique.

Color Constancy

Constructing Neural Network-Based Models for Simulating Dynamical Systems

1 code implementation2 Nov 2021 Christian Møldrup Legaard, Thomas Schranz, Gerald Schweiger, Ján Drgoňa, Basak Falay, Cláudio Gomes, Alexandros Iosifidis, Mahdi Abkar, Peter Gorm Larsen

Dynamical systems see widespread use in natural sciences like physics, biology, chemistry, as well as engineering disciplines such as circuit analysis, computational fluid dynamics, and control.

On Quantitative Evaluations of Counterfactuals

1 code implementation30 Oct 2021 Frederik Hvilshøj, Alexandros Iosifidis, Ira Assent

As counterfactual examples become increasingly popular for explaining decisions of deep learning models, it is essential to understand what properties quantitative evaluation metrics do capture and equally important what they do not capture.

counterfactual

Improving Neural Network Generalization via Promoting Within-Layer Diversity

no code implementations29 Sep 2021 Firas Laakom, Jenni Raitoharju, Alexandros Iosifidis, Moncef Gabbouj

Neural networks are composed of multiple layers arranged in a hierarchical structure jointly trained with a gradient-based optimization, where the errors are back-propagated from the last layer back to the first one.

Remote Multilinear Compressive Learning with Adaptive Compression

no code implementations2 Sep 2021 Dat Thanh Tran, Moncef Gabbouj, Alexandros Iosifidis

By developing compressive sensing and learning models that can operate with an adaptive compression rate, we can maximize the informational content throughput of the whole application.

Compressive Sensing

Bilinear Input Normalization for Neural Networks in Financial Forecasting

1 code implementation1 Sep 2021 Dat Thanh Tran, Juho Kanniainen, Moncef Gabbouj, Alexandros Iosifidis

Data normalization is one of the most important preprocessing steps when building a machine learning model, especially when the model of interest is a deep neural network.

Time Series Time Series Analysis

Multi-Exit Vision Transformer for Dynamic Inference

no code implementations29 Jun 2021 Arian Bakhtiarnia, Qi Zhang, Alexandros Iosifidis

In this work, we propose seven different architectures for early exit branches that can be used for dynamic inference in Vision Transformer backbones.

Edge-computing

Automatic Main Character Recognition for Photographic Studies

no code implementations16 Jun 2021 Mert Seker, Anssi Männistö, Alexandros Iosifidis, Jenni Raitoharju

Identifying the main character in images plays an important role in traditional photographic studies and media analysis, but the task is performed manually and can be slow and laborious.

Binary Classification Pose Estimation

Learning distinct features helps, provably

no code implementations10 Jun 2021 Firas Laakom, Jenni Raitoharju, Alexandros Iosifidis, Moncef Gabbouj

We study the diversity of the features learned by a two-layer neural network trained with the least squares loss.

Generalization Bounds

Progressive Spatio-Temporal Bilinear Network with Monte Carlo Dropout for Landmark-based Facial Expression Recognition with Uncertainty Estimation

1 code implementation8 Jun 2021 Negar Heidari, Alexandros Iosifidis

In this paper, we propose a method which learns an optimized compact network topology for real-time facial expression recognition utilizing localized facial landmark features.

Facial Expression Recognition Facial Expression Recognition (FER)

Continual 3D Convolutional Neural Networks for Real-time Processing of Videos

1 code implementation31 May 2021 Lukas Hedegaard, Alexandros Iosifidis

We introduce Continual 3D Convolutional Neural Networks (Co3D CNNs), a new computational formulation of spatio-temporal 3D CNNs, in which videos are processed frame-by-frame rather than by clip.

Action Classification Video Recognition

Analysis of voxel-based 3D object detection methods efficiency for real-time embedded systems

1 code implementation21 May 2021 Illia Oleksiienko, Alexandros Iosifidis

This means that the methods can achieve a speed-up of $40$-$60\%$ by restricting operation to near objects while not sacrificing much in performance.

3D Object Detection object-detection

Single-Layer Vision Transformers for More Accurate Early Exits with Less Overhead

no code implementations19 May 2021 Arian Bakhtiarnia, Qi Zhang, Alexandros Iosifidis

Deploying deep learning models in time-critical applications with limited computational resources, for instance in edge computing systems and IoT networks, is a challenging task that often relies on dynamic inference methods such as early exiting.

Audio Classification Crowd Counting +1

Improving the Accuracy of Early Exits in Multi-Exit Architectures via Curriculum Learning

no code implementations21 Apr 2021 Arian Bakhtiarnia, Qi Zhang, Alexandros Iosifidis

Deploying deep learning services for time-sensitive and resource-constrained settings such as IoT using edge computing systems is a challenging task that requires dynamic adjustment of inference time.

Edge-computing

Knowledge Distillation By Sparse Representation Matching

1 code implementation31 Mar 2021 Dat Thanh Tran, Moncef Gabbouj, Alexandros Iosifidis

Knowledge Distillation refers to a class of methods that transfers the knowledge from a teacher network to a student network.

Knowledge Distillation Representation Learning

ECINN: Efficient Counterfactuals from Invertible Neural Networks

1 code implementation25 Mar 2021 Frederik Hvilshøj, Alexandros Iosifidis, Ira Assent

Counterfactual examples identify how inputs can be altered to change the predicted class of a classifier, thus opening up the black-box nature of, e. g., deep neural networks.

counterfactual Image Classification

Visualising Deep Network's Time-Series Representations

no code implementations12 Mar 2021 Błażej Leporowski, Alexandros Iosifidis

Despite the popularisation of machine learning models, more often than not, they still operate as black boxes with no insight into what is happening inside the model.

Time Series Time Series Analysis +1

Automatic Social Distance Estimation From Images: Performance Evaluation, Test Benchmark, and Algorithm

1 code implementation11 Mar 2021 Mert Seker, Anssi Männistö, Alexandros Iosifidis, Jenni Raitoharju

The World Health Organization (WHO) has provided guidelines on how to reduce the spread of the virus and one of the most important measures is social distancing.

Human Detection object-detection +2

Adaptive Weighting Scheme for Automatic Time-Series Data Augmentation

no code implementations16 Feb 2021 Elizabeth Fons, Paula Dawson, Xiao-jun Zeng, John Keane, Alexandros Iosifidis

Data augmentation methods have been shown to be a fundamental technique to improve generalization in tasks such as image, text and audio classification.

Audio Classification Data Augmentation +5

Ensembling object detectors for image and video data analysis

no code implementations9 Feb 2021 Kateryna Chumachenko, Jenni Raitoharju, Alexandros Iosifidis, Moncef Gabbouj

In this paper, we propose a method for ensembling the outputs of multiple object detectors for improving detection performance and precision of bounding boxes on image data.

Object object-detection +1

AURSAD: Universal Robot Screwdriving Anomaly Detection Dataset

no code implementations2 Feb 2021 Błażej Leporowski, Daniella Tola, Casper Hansen, Alexandros Iosifidis

In order to do so, first a dataset that fully describes the operation of an industrial robot performing automated screwdriving must be available.

Anomaly Detection

ON NEURAL NETWORK GENERALIZATION VIA PROMOTING WITHIN-LAYER ACTIVATION DIVERSITY

no code implementations1 Jan 2021 Firas Laakom, Jenni Raitoharju, Alexandros Iosifidis, Moncef Gabbouj

During the last decade, neural networks have been intensively used to tackle various problems and they have often led to state-of-the-art results.

Progressive Spatio-Temporal Graph Convolutional Network for Skeleton-Based Human Action Recognition

no code implementations11 Nov 2020 Negar Heidari, Alexandros Iosifidis

Graph convolutional networks (GCNs) have been very successful in skeleton-based human action recognition where the sequence of skeletons is modeled as a graph.

Action Recognition Temporal Action Localization

On the spatial attention in Spatio-Temporal Graph Convolutional Networks for skeleton-based human action recognition

1 code implementation7 Nov 2020 Negar Heidari, Alexandros Iosifidis

Graph convolutional networks (GCNs) achieved promising performance in skeleton-based human action recognition by modeling a sequence of skeletons as a spatio-temporal graph.

Action Recognition Temporal Action Localization

Evaluating data augmentation for financial time series classification

1 code implementation28 Oct 2020 Elizabeth Fons, Paula Dawson, Xiao-jun Zeng, John Keane, Alexandros Iosifidis

Data augmentation methods in combination with deep neural networks have been used extensively in computer vision on classification tasks, achieving great success; however, their use in time series classification is still at an early stage.

Classification Data Augmentation +4

Augmenting transferred representations for stock classification

no code implementations28 Oct 2020 Elizabeth Fons, Paula Dawson, Xiao-jun Zeng, John Keane, Alexandros Iosifidis

In this paper we show that using transfer learning can help with this task, by pre-training a model to extract universal features on the full universe of stocks of the S$\&$P500 index and then transferring it to another model to directly learn a trading rule.

Classification Data Augmentation +4

Temporal Attention-Augmented Graph Convolutional Network for Efficient Skeleton-Based Human Action Recognition

no code implementations23 Oct 2020 Negar Heidari, Alexandros Iosifidis

In this paper, we propose a temporal attention module (TAM) for increasing the efficiency in skeleton-based action recognition by selecting the most informative skeletons of an action at the early layers of the network.

Action Recognition Skeleton Based Action Recognition +1

Performance Indicator in Multilinear Compressive Learning

no code implementations22 Sep 2020 Dat Thanh Tran, Moncef Gabbouj, Alexandros Iosifidis

Recently, the Multilinear Compressive Learning (MCL) framework was proposed to efficiently optimize the sensing and learning steps when working with multidimensional signals, i. e. tensors.

Compressive Sensing

Graph Embedding with Data Uncertainty

no code implementations1 Sep 2020 Firas Laakom, Jenni Raitoharju, Nikolaos Passalis, Alexandros Iosifidis, Moncef Gabbouj

spectral-based subspace learning is a common data preprocessing step in many machine learning pipelines.

Graph Embedding

Exploiting Heterogeneity in Operational Neural Networks by Synaptic Plasticity

no code implementations21 Aug 2020 Serkan Kiranyaz, Junaid Malik, Habib Ben Abdallah, Turker Ince, Alexandros Iosifidis, Moncef Gabbouj

As a heterogenous network model, ONNs are based on a generalized neuron model that can encapsulate any set of non-linear operators to boost diversity and to learn highly complex and multi-modal functions or spaces with minimal network complexity and training data.

Learning Theory

Attention-based Neural Bag-of-Features Learning for Sequence Data

1 code implementation25 May 2020 Dat Thanh Tran, Nikolaos Passalis, Anastasios Tefas, Moncef Gabbouj, Alexandros Iosifidis

In this paper, we propose 2D-Attention (2DA), a generic attention formulation for sequence data, which acts as a complementary computation block that can detect and focus on relevant sources of information for the given learning objective.

Medical Diagnosis

Probabilistic Color Constancy

no code implementations6 May 2020 Firas Laakom, Jenni Raitoharju, Alexandros Iosifidis, Uygar Tuna, Jarno Nikkanen, Moncef Gabbouj

In this paper, we propose a novel unsupervised color constancy method, called Probabilistic Color Constancy (PCC).

Color Constancy

Self-Organized Operational Neural Networks with Generative Neurons

2 code implementations24 Apr 2020 Serkan Kiranyaz, Junaid Malik, Habib Ben Abdallah, Turker Ince, Alexandros Iosifidis, Moncef Gabbouj

However, Greedy Iterative Search (GIS) method, which is the search method used to find optimal operators in ONNs takes many training sessions to find a single operator set per layer.

Computational Efficiency

Saliency-based Weighted Multi-label Linear Discriminant Analysis

no code implementations8 Apr 2020 Lei Xu, Jenni Raitoharju, Alexandros Iosifidis, Moncef Gabbouj

The proposed method is based on a probabilistic model for defining the weights of individual samples in a weighted multi-label LDA approach.

Classification General Classification +1

Progressive Graph Convolutional Networks for Semi-Supervised Node Classification

1 code implementation27 Mar 2020 Negar Heidari, Alexandros Iosifidis

Graph convolutional networks have been successful in addressing graph-based tasks such as semi-supervised node classification.

Classification General Classification +1

Not all domains are equally complex: Adaptive Multi-Domain Learning

no code implementations25 Mar 2020 Ali Senhaji, Jenni Raitoharju, Moncef Gabbouj, Alexandros Iosifidis

The most common approach in multi-domain learning is to form a domain agnostic model, the parameters of which are shared among all domains, and learn a small number of extra domain-specific parameters for each individual new domain.

Ellipsoidal Subspace Support Vector Data Description

1 code implementation20 Mar 2020 Fahad Sohrab, Jenni Raitoharju, Alexandros Iosifidis, Moncef Gabbouj

In this paper, we propose a novel method for transforming data into a low-dimensional space optimized for one-class classification.

General Classification One-Class Classification

Subset Sampling For Progressive Neural Network Learning

1 code implementation17 Feb 2020 Dat Thanh Tran, Moncef Gabbouj, Alexandros Iosifidis

Progressive Neural Network Learning is a class of algorithms that incrementally construct the network's topology and optimize its parameters based on the training data.

Face Recognition

Multilinear Compressive Learning with Prior Knowledge

1 code implementation17 Feb 2020 Dat Thanh Tran, Moncef Gabbouj, Alexandros Iosifidis

Extensive experiments demonstrate that the proposed knowledge transfer method can effectively train MCL models to compressively sense and synthesize better features for the learning tasks with improved performances, especially when the complexity of the learning task increases.

Compressive Sensing Transfer Learning

Incremental Fast Subclass Discriminant Analysis

no code implementations11 Feb 2020 Kateryna Chumachenko, Jenni Raitoharju, Moncef Gabbouj, Alexandros Iosifidis

This paper proposes an incremental solution to Fast Subclass Discriminant Analysis (fastSDA).

Text-to-image synthesis method evaluation based on visual patterns

no code implementations31 Oct 2019 William Lund Sommer, Alexandros Iosifidis

Visual concepts are determined by clustering the real image representations, and are subsequently used to evaluate the similarity of the generated images to the real ones by classifying them to the closest visual concept.

Clustering Image Generation

Null Space Analysis for Class-Specific Discriminant Learning

no code implementations13 Aug 2019 Jenni Raitoharju, Alexandros Iosifidis

In this paper, we carry out null space analysis for Class-Specific Discriminant Analysis (CSDA) and formulate a number of solutions based on the analysis.

Dimensionality Reduction

Bag of Color Features For Color Constancy

1 code implementation11 Jun 2019 Firas Laakom, Nikolaos Passalis, Jenni Raitoharju, Jarno Nikkanen, Anastasios Tefas, Alexandros Iosifidis, Moncef Gabbouj

To further improve the illumination estimation accuracy, we propose a novel attention mechanism for the BoCF model with two variants based on self-attention.

Color Constancy

Color Constancy Convolutional Autoencoder

no code implementations4 Jun 2019 Firas Laakom, Jenni Raitoharju, Alexandros Iosifidis, Jarno Nikkanen, Moncef Gabbouj

In this paper, we study the importance of pre-training for the generalization capability in the color constancy problem.

Color Constancy Unsupervised Pre-training

Multilinear Compressive Learning

2 code implementations17 May 2019 Dat Thanh Tran, Mehmet Yamac, Aysen Degerli, Moncef Gabbouj, Alexandros Iosifidis

Compressive Learning is an emerging topic that combines signal acquisition via compressive sensing and machine learning to perform inference tasks directly on a small number of measurements.

Compressive Sensing Face Recognition

Speed-up and multi-view extensions to Subclass Discriminant Analysis

1 code implementation2 May 2019 Kateryna Chumachenko, Jenni Raitoharju, Alexandros Iosifidis, Moncef Gabbouj

We show that by exploiting the structure of the between-class Laplacian matrix, the eigendecomposition step can be substituted with a much faster process.

Graph Embedding regression

Machine Learning Based Analysis of Finnish World War II Photographers

1 code implementation22 Apr 2019 Kateryna Chumachenko, Anssi Männistö, Alexandros Iosifidis, Jenni Raitoharju

In this paper, we demonstrate the benefits of using state-of-the-art machine learning methods in the analysis of historical photo archives.

BIG-bench Machine Learning

Multimodal Subspace Support Vector Data Description

1 code implementation16 Apr 2019 Fahad Sohrab, Jenni Raitoharju, Alexandros Iosifidis, Moncef Gabbouj

In this paper, we propose a novel method for projecting data from multiple modalities to a new subspace optimized for one-class classification.

General Classification One-Class Classification

Feature Engineering for Mid-Price Prediction with Deep Learning

no code implementations10 Apr 2019 Adamantios Ntakaris, Giorgio Mirone, Juho Kanniainen, Moncef Gabbouj, Alexandros Iosifidis

Mid-price movement prediction based on limit order book (LOB) data is a challenging task due to the complexity and dynamics of the LOB.

Feature Engineering

3D Quantum Cuts for Automatic Segmentation of Porous Media in Tomography Images

no code implementations9 Apr 2019 Junaid Malik, Serkan Kiranyaz, Riyadh Al-Raoush, Olivier Monga, Patricia Garnier, Sebti Foufou, Abdelaziz Bouras, Alexandros Iosifidis, Moncef Gabbouj, Philippe C. Baveye

Binary segmentation of volumetric images of porous media is a crucial step towards gaining a deeper understanding of the factors governing biogeochemical processes at minute scales.

Clustering Image Segmentation +2

Data-driven Neural Architecture Learning For Financial Time-series Forecasting

no code implementations5 Mar 2019 Dat Thanh Tran, Juho Kanniainen, Moncef Gabbouj, Alexandros Iosifidis

Forecasting based on financial time-series is a challenging task since most real-world data exhibits nonstationary property and nonlinear dependencies.

Time Series Time Series Forecasting +1

Operational Neural Networks

no code implementations15 Feb 2019 Serkan Kiranyaz, Turker Ince, Alexandros Iosifidis, Moncef Gabbouj

In order to address this drawback and also to accomplish a more generalized model over the convolutional neurons, this study proposes a novel network model, called Operational Neural Networks (ONNs), which can be heterogeneous and encapsulate neurons with any set of operators to boost diversity and to learn highly complex and multi-modal functions or spaces with minimal network complexity and training data.

Temporal Logistic Neural Bag-of-Features for Financial Time series Forecasting leveraging Limit Order Book Data

no code implementations24 Jan 2019 Nikolaos Passalis, Anastasios Tefas, Juho Kanniainen, Moncef Gabbouj, Alexandros Iosifidis

However, combining existing BoF formulations with deep feature extractors pose significant challenges: the distribution of the input features is not stationary, tuning the hyper-parameters of the model can be especially difficult and the normalizations involved in the BoF model can cause significant instabilities during the training process.

Density Estimation Time Series +1

Class Mean Vector Component and Discriminant Analysis

no code implementations14 Dec 2018 Alexandros Iosifidis

The kernel matrix used in kernel methods encodes all the information required for solving complex nonlinear problems defined on data representations in the input space using simple, but implicitly defined, solutions.

Dimensionality Reduction

Probabilistic Class-Specific Discriminant Analysis

no code implementations14 Dec 2018 Alexandros Iosifidis

In this paper we formulate a probabilistic model for class-specific discriminant subspace learning.

Classification General Classification

Progressive Operational Perceptron with Memory

1 code implementation20 Aug 2018 Dat Thanh Tran, Serkan Kiranyaz, Moncef Gabbouj, Alexandros Iosifidis

Generalized Operational Perceptron (GOP) was proposed to generalize the linear neuron model in the traditional Multilayer Perceptron (MLP) and this model can mimic the synaptic connections of the biological neurons that have nonlinear neurochemical behaviours.

Multi-layer Kernel Ridge Regression for One-class Classification

no code implementations20 May 2018 Chandan Gautam, Aruna Tiwari, Sundaram Suresh, Alexandros Iosifidis

In this paper, a multi-layer architecture (in a hierarchical fashion) by stacking various Kernel Ridge Regression (KRR) based Auto-Encoder for one-class classification is proposed and is referred as MKOC.

Classification General Classification +3

Heterogeneous Multilayer Generalized Operational Perceptron

1 code implementation13 Apr 2018 Dat Thanh Tran, Serkan Kiranyaz, Moncef Gabbouj, Alexandros Iosifidis

Previously, Generalized Operational Perceptron (GOP) was proposed to extend conventional perceptron model by defining a diverse set of neuronal activities to imitate a generalized model of biological neurons.

Weighted Linear Discriminant Analysis based on Class Saliency Information

no code implementations19 Feb 2018 Lei Xu, Alexandros Iosifidis, Moncef Gabbouj

In this paper, we propose a new variant of Linear Discriminant Analysis to overcome underlying drawbacks of traditional LDA and other LDA variants targeting problems involving imbalanced classes.

General Classification Image Classification +1

Subspace Support Vector Data Description

1 code implementation12 Feb 2018 Fahad Sohrab, Jenni Raitoharju, Moncef Gabbouj, Alexandros Iosifidis

The method iteratively optimizes the data mapping along with data description in order to define a compact class representation in a low-dimensional feature space.

Classification General Classification +1

Temporal Attention augmented Bilinear Network for Financial Time-Series Data Analysis

1 code implementation4 Dec 2017 Dat Thanh Tran, Alexandros Iosifidis, Juho Kanniainen, Moncef Gabbouj

Financial time-series forecasting has long been a challenging problem because of the inherently noisy and stochastic nature of the market.

Time Series Time Series Forecasting

Multilinear Class-Specific Discriminant Analysis

no code implementations29 Oct 2017 Dat Thanh Tran, Moncef Gabbouj, Alexandros Iosifidis

There has been a great effort to transfer linear discriminant techniques that operate on vector data to high-order data, generally referred to as Multilinear Discriminant Analysis (MDA) techniques.

Stock Price Prediction

Improving Efficiency in Convolutional Neural Network with Multilinear Filters

no code implementations28 Sep 2017 Dat Thanh Tran, Alexandros Iosifidis, Moncef Gabbouj

The excellent performance of deep neural networks has enabled us to solve several automatization problems, opening an era of autonomous devices.

Tensor Representation in High-Frequency Financial Data for Price Change Prediction

no code implementations5 Sep 2017 Dat Thanh Tran, Martin Magris, Juho Kanniainen, Moncef Gabbouj, Alexandros Iosifidis

Nowadays, with the availability of massive amount of trade data collected, the dynamics of the financial markets pose both a challenge and an opportunity for high frequency traders.

Time Series Time Series Analysis +1

Neural Class-Specific Regression for face verification

no code implementations31 Aug 2017 Guanqun Cao, Alexandros Iosifidis, Moncef Gabbouj

Face verification is a problem approached in the literature mainly using nonlinear class-specific subspace learning techniques.

Face Verification regression

Human experts vs. machines in taxa recognition

no code implementations23 Aug 2017 Johanna Ärje, Jenni Raitoharju, Alexandros Iosifidis, Ville Tirronen, Kristian Meissner, Moncef Gabbouj, Serkan Kiranyaz, Salme Kärkkäinen

Contrary to previous findings in the literature, we find that for machines following a typical flat classification approach commonly used in machine learning performs better than forcing machines to adopt a hierarchical, local per parent node approach used by human taxonomic experts ($\overline{CE}=13. 8\%$).

BIG-bench Machine Learning General Classification +1

Probabilistic Saliency Estimation

no code implementations13 Sep 2016 Caglar Aytekin, Alexandros Iosifidis, Moncef Gabbouj

In this paper, we model the salient object detection problem under a probabilistic framework encoding the boundary connectivity saliency cue and smoothness constraints in an optimization problem.

Object object-detection +4

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