Search Results for author: Ioannis Kompatsiaris

Found 29 papers, 14 papers with code

User Identity Linkage in Social Media Using Linguistic and Social Interaction Features

no code implementations22 Aug 2023 Despoina Chatzakou, Juan Soler-Company, Theodora Tsikrika, Leo Wanner, Stefanos Vrochidis, Ioannis Kompatsiaris

Social media users often hold several accounts in their effort to multiply the spread of their thoughts, ideas, and viewpoints.

AI and Non AI Assessments for Dementia

no code implementations30 Jun 2023 Mahboobeh, Parsapoor, Hamed Ghodrati, Vincenzo Dentamaro, Christopher R. Madan, Ioulietta Lazarou, Spiros Nikolopoulos, Ioannis Kompatsiaris

Thus, this paper, which can be readable by both clinicians and AI engineers, fills the gap in the literature in explaining the existing solutions for the recognition of dementia to clinicians, as well as the techniques used and the most widespread dementia datasets to AI engineers.

Improving Synthetically Generated Image Detection in Cross-Concept Settings

1 code implementation24 Apr 2023 Pantelis Dogoulis, Giorgos Kordopatis-Zilos, Ioannis Kompatsiaris, Symeon Papadopoulos

New advancements for the detection of synthetic images are critical for fighting disinformation, as the capabilities of generative AI models continuously evolve and can lead to hyper-realistic synthetic imagery at unprecedented scale and speed.

Multilingual Alzheimer's Dementia Recognition through Spontaneous Speech: a Signal Processing Grand Challenge

no code implementations13 Jan 2023 Saturnino Luz, Fasih Haider, Davida Fromm, Ioulietta Lazarou, Ioannis Kompatsiaris, Brian MacWhinney

This Signal Processing Grand Challenge (SPGC) targets a difficult automatic prediction problem of societal and medical relevance, namely, the detection of Alzheimer's Dementia (AD).

A Multi-Stream Fusion Network for Image Splicing Localization

no code implementations2 Dec 2022 Maria Siopi, Giorgos Kordopatis-Zilos, Polychronis Charitidis, Ioannis Kompatsiaris, Symeon Papadopoulos

In this paper, we address the problem of image splicing localization with a multi-stream network architecture that processes the raw RGB image in parallel with other handcrafted forensic signals.

VICTOR: Visual Incompatibility Detection with Transformers and Fashion-specific contrastive pre-training

1 code implementation27 Jul 2022 Stefanos-Iordanis Papadopoulos, Christos Koutlis, Symeon Papadopoulos, Ioannis Kompatsiaris

For fashion outfits to be considered aesthetically pleasing, the garments that constitute them need to be compatible in terms of visual aspects, such as style, category and color.

Binary Classification Recommendation Systems

InDistill: Information flow-preserving knowledge distillation for model compression

1 code implementation20 May 2022 Ioannis Sarridis, Christos Koutlis, Giorgos Kordopatis-Zilos, Ioannis Kompatsiaris, Symeon Papadopoulos

In this paper we introduce InDistill, a model compression approach that combines knowledge distillation and channel pruning in a unified framework for the transfer of the critical information flow paths from a heavyweight teacher to a lightweight student.

Knowledge Distillation Model Compression

The MeVer DeepFake Detection Service: Lessons Learnt from Developing and Deploying in the Wild

no code implementations27 Apr 2022 Spyridon Baxevanakis, Giorgos Kordopatis-Zilos, Panagiotis Galopoulos, Lazaros Apostolidis, Killian Levacher, Ipek B. Schlicht, Denis Teyssou, Ioannis Kompatsiaris, Symeon Papadopoulos

Enabled by recent improvements in generation methodologies, DeepFakes have become mainstream due to their increasingly better visual quality, the increase in easy-to-use generation tools and the rapid dissemination through social media.

DeepFake Detection Face Swapping

Multimodal Quasi-AutoRegression: Forecasting the visual popularity of new fashion products

no code implementations8 Apr 2022 Stefanos I. Papadopoulos, Christos Koutlis, Symeon Papadopoulos, Ioannis Kompatsiaris

We employ the product's target attributes time series as a proxy of temporal popularity patterns, mitigating the lack of historical data, while exogenous time series help capture trends among interrelated attributes.

Image Captioning Image Classification +4

p2pGNN: A Decentralized Graph Neural Network for Node Classification in Peer-to-Peer Networks

1 code implementation29 Nov 2021 Emmanouil Krasanakis, Symeon Papadopoulos, Ioannis Kompatsiaris

In this work, we aim to classify nodes of unstructured peer-to-peer networks with communication uncertainty, such as users of decentralized social networks.

Node Classification

pygrank: A Python Package for Graph Node Ranking

1 code implementation18 Oct 2021 Emmanouil Krasanakis, Symeon Papadopoulos, Ioannis Kompatsiaris, Andreas Symeonidis

We introduce pygrank, an open source Python package to define, run and evaluate node ranking algorithms.

A Survey on Bias in Visual Datasets

no code implementations16 Jul 2021 Simone Fabbrizzi, Symeon Papadopoulos, Eirini Ntoutsi, Ioannis Kompatsiaris

Hence, this work aims to: i) describe the biases that might manifest in visual datasets; ii) review the literature on methods for bias discovery and quantification in visual datasets; iii) discuss existing attempts to collect bias-aware visual datasets.

DnS: Distill-and-Select for Efficient and Accurate Video Indexing and Retrieval

1 code implementation24 Jun 2021 Giorgos Kordopatis-Zilos, Christos Tzelepis, Symeon Papadopoulos, Ioannis Kompatsiaris, Ioannis Patras

In this work, we propose a Knowledge Distillation framework, called Distill-and-Select (DnS), that starting from a well-performing fine-grained Teacher Network learns: a) Student Networks at different retrieval performance and computational efficiency trade-offs and b) a Selector Network that at test time rapidly directs samples to the appropriate student to maintain both high retrieval performance and high computational efficiency.

Computational Efficiency Knowledge Distillation +2

Audio-based Near-Duplicate Video Retrieval with Audio Similarity Learning

1 code implementation17 Oct 2020 Pavlos Avgoustinakis, Giorgos Kordopatis-Zilos, Symeon Papadopoulos, Andreas L. Symeonidis, Ioannis Kompatsiaris

For the robust similarity calculation between two videos, we first extract representative audio-based video descriptors by leveraging transfer learning based on a Convolutional Neural Network (CNN) trained on a large scale dataset of audio events, and then we calculate the similarity matrix derived from the pairwise similarity of these descriptors.

Retrieval Transfer Learning +1

Investigating the Impact of Pre-processing and Prediction Aggregation on the DeepFake Detection Task

no code implementations12 Jun 2020 Polychronis Charitidis, Giorgos Kordopatis-Zilos, Symeon Papadopoulos, Ioannis Kompatsiaris

In this paper, we propose a pre-processing step to improve the training data quality and examine its effect on the performance of DeepFake detection.

DeepFake Detection Face Swapping

MuSe 2020 -- The First International Multimodal Sentiment Analysis in Real-life Media Challenge and Workshop

1 code implementation30 Apr 2020 Lukas Stappen, Alice Baird, Georgios Rizos, Panagiotis Tzirakis, Xinchen Du, Felix Hafner, Lea Schumann, Adria Mallol-Ragolta, Björn W. Schuller, Iulia Lefter, Erik Cambria, Ioannis Kompatsiaris

Multimodal Sentiment Analysis in Real-life Media (MuSe) 2020 is a Challenge-based Workshop focusing on the tasks of sentiment recognition, as well as emotion-target engagement and trustworthiness detection by means of more comprehensively integrating the audio-visual and language modalities.

Emotion Recognition Multimodal Sentiment Analysis

ViSiL: Fine-grained Spatio-Temporal Video Similarity Learning

1 code implementation ICCV 2019 Giorgos Kordopatis-Zilos, Symeon Papadopoulos, Ioannis Patras, Ioannis Kompatsiaris

Subsequently, the similarity matrix between all video frames is fed to a four-layer CNN, and then summarized using Chamfer Similarity (CS) into a video-to-video similarity score -- this avoids feature aggregation before the similarity calculation between videos and captures the temporal similarity patterns between matching frame sequences.

ISVR Retrieval +2

FIVR: Fine-grained Incident Video Retrieval

1 code implementation11 Sep 2018 Giorgos Kordopatis-Zilos, Symeon Papadopoulos, Ioannis Patras, Ioannis Kompatsiaris

To create the dataset, we devise a process for the collection of YouTube videos based on major news events from recent years crawled from Wikipedia and deploy a retrieval pipeline for the automatic selection of query videos based on their estimated suitability as benchmarks.

Benchmarking Retrieval +1

A Two-Level Classification Approach for Detecting Clickbait Posts using Text-Based Features

1 code implementation23 Oct 2017 Olga Papadopoulou, Markos Zampoglou, Symeon Papadopoulos, Ioannis Kompatsiaris

The detector is based almost exclusively on text-based features taken from previous work on clickbait detection, our own work on fake post detection, and features we designed specifically for the challenge.

Clickbait Detection Fake News Detection +2

The Dem@Care Experiments and Datasets: a Technical Report

no code implementations17 Dec 2016 Anastasios Karakostas, Alexia Briassouli, Konstantinos Avgerinakis, Ioannis Kompatsiaris, Magda Tsolaki

The objective of Dem@Care is the development of a complete system providing personal health services to people with dementia, as well as medical professionals and caregivers, by using a multitude of sensors, for context-aware, multi-parametric monitoring of lifestyle, ambient environment, and health parameters.

Decision Making

Comparative evaluation of state-of-the-art algorithms for SSVEP-based BCIs

3 code implementations2 Feb 2016 Vangelis P. Oikonomou, Georgios Liaros, Kostantinos Georgiadis, Elisavet Chatzilari, Katerina Adam, Spiros Nikolopoulos, Ioannis Kompatsiaris

Brain-computer interfaces (BCIs) have been gaining momentum in making human-computer interaction more natural, especially for people with neuro-muscular disabilities.

EEG feature selection +1

Monitoring Term Drift Based on Semantic Consistency in an Evolving Vector Field

1 code implementation5 Feb 2015 Peter Wittek, Sándor Darányi, Efstratios Kontopoulos, Theodoros Moysiadis, Ioannis Kompatsiaris

Based on the Aristotelian concept of potentiality vs. actuality allowing for the study of energy and dynamics in language, we propose a field approach to lexical analysis.

Lexical Analysis Philosophy

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