Search Results for author: Vasileios Mezaris

Found 22 papers, 14 papers with code

Visual and audio scene classification for detecting discrepancies in video: a baseline method and experimental protocol

no code implementations1 May 2024 Konstantinos Apostolidis, Jakob Abesser, Luca Cuccovillo, Vasileios Mezaris

This paper presents a baseline approach and an experimental protocol for a specific content verification problem: detecting discrepancies between the audio and video modalities in multimedia content.

Scene Classification

Towards Quantitative Evaluation of Explainable AI Methods for Deepfake Detection

no code implementations29 Apr 2024 Konstantinos Tsigos, Evlampios Apostolidis, Spyridon Baxevanakis, Symeon Papadopoulos, Vasileios Mezaris

The findings of our quantitative and qualitative evaluations document the advanced performance of the LIME explanation method against the other compared ones, and indicate this method as the most appropriate for explaining the decisions of the utilized deepfake detector.

DeepFake Detection Face Swapping

T-TAME: Trainable Attention Mechanism for Explaining Convolutional Networks and Vision Transformers

no code implementations7 Mar 2024 Mariano V. Ntrougkas, Nikolaos Gkalelis, Vasileios Mezaris

While some techniques for generating explanations have been proposed, primarily for Convolutional Neural Networks, adapting such techniques to the new paradigm of Vision Transformers is non-trivial.

Image Classification

Facilitating the Production of Well-tailored Video Summaries for Sharing on Social Media

no code implementations5 Dec 2023 Evlampios Apostolidis, Konstantinos Apostolidis, Vasileios Mezaris

This paper presents a web-based tool that facilitates the production of tailored summaries for online sharing on social media.

Video Summarization

Exploring Multi-Modal Fusion for Image Manipulation Detection and Localization

1 code implementation4 Dec 2023 Konstantinos Triaridis, Vasileios Mezaris

Recent image manipulation localization and detection techniques usually leverage forensic artifacts and traces that are produced by a noise-sensitive filter, such as SRM and Bayar convolution.

Detecting Image Manipulation Image Forensics +4

Filter-Pruning of Lightweight Face Detectors Using a Geometric Median Criterion

1 code implementation28 Nov 2023 Konstantinos Gkrispanis, Nikolaos Gkalelis, Vasileios Mezaris

Face detectors are becoming a crucial component of many applications, including surveillance, that often have to run on edge devices with limited processing power and memory.

Face Detection Network Pruning

Gated-ViGAT: Efficient Bottom-Up Event Recognition and Explanation Using a New Frame Selection Policy and Gating Mechanism

1 code implementation18 Jan 2023 Nikolaos Gkalelis, Dimitrios Daskalakis, Vasileios Mezaris

In this paper, Gated-ViGAT, an efficient approach for video event recognition, utilizing bottom-up (object) information, a new frame sampling policy and a gating mechanism is proposed.

Graph Attention

TAME: Attention Mechanism Based Feature Fusion for Generating Explanation Maps of Convolutional Neural Networks

1 code implementation18 Jan 2023 Mariano Ntrougkas, Nikolaos Gkalelis, Vasileios Mezaris

TAME can easily be applied to any convolutional neural network (CNN) by streamlining the optimization of the attention mechanism's training method and the selection of target model's feature maps.

Learning Visual Explanations for DCNN-Based Image Classifiers Using an Attention Mechanism

1 code implementation22 Sep 2022 Ioanna Gkartzonika, Nikolaos Gkalelis, Vasileios Mezaris

In this paper two new learning-based eXplainable AI (XAI) methods for deep convolutional neural network (DCNN) image classifiers, called L-CAM-Fm and L-CAM-Img, are proposed.

Explainable Artificial Intelligence (XAI)

ViGAT: Bottom-up event recognition and explanation in video using factorized graph attention network

1 code implementation20 Jul 2022 Nikolaos Gkalelis, Dimitrios Daskalakis, Vasileios Mezaris

In this paper a pure-attention bottom-up approach, called ViGAT, that utilizes an object detector together with a Vision Transformer (ViT) backbone network to derive object and frame features, and a head network to process these features for the task of event recognition and explanation in video, is proposed.

Graph Attention

Summarizing Videos using Concentrated Attention and Considering the Uniqueness and Diversity of the Video Frames

1 code implementation ACM ICMR 2022 Evlampios Apostolidis, Georgios Balaouras, Vasileios Mezaris, Ioannis Patras

Instead of simply modeling the frames' dependencies based on global attention, our method integrates a concentrated attention mechanism that is able to focus on non-overlapping blocks in the main diagonal of the attention matrix, and to enrich the existing information by extracting and exploiting knowledge about the uniqueness and diversity of the associated frames of the video.

Benchmarking Unsupervised Video Summarization

Video Summarization Using Deep Neural Networks: A Survey

no code implementations15 Jan 2021 Evlampios Apostolidis, Eleni Adamantidou, Alexandros I. Metsai, Vasileios Mezaris, Ioannis Patras

Video summarization technologies aim to create a concise and complete synopsis by selecting the most informative parts of the video content.

Video Summarization

Unsupervised Video Summarization via Attention-Driven Adversarial Learning

1 code implementation MultiMedia Modeling (MMM) 2019 Evlampios Apostolidis, Eleni Adamantidou, Alexandros I. Metsai, Vasileios Mezaris, Ioannis Patras

Experimental evaluation on two datasets (SumMe and TVSum) documents the contribution of the attention auto-encoder to faster and more stable training of the model, resulting in a significant performance improvement with respect to the original model and demonstrating the competitiveness of the proposed SUM-GAN-AAE against the state of the art.

Unsupervised Video Summarization

Accelerated kernel discriminant analysis

no code implementations27 Apr 2015 Nikolaos Gkalelis, Vasileios Mezaris

In this paper, using a novel matrix factorization and simultaneous reduction to diagonal form approach (or in short simultaneous reduction approach), Accelerated Kernel Discriminant Analysis (AKDA) and Accelerated Kernel Subclass Discriminant Analysis (AKSDA) are proposed.

General Classification

Linear Maximum Margin Classifier for Learning from Uncertain Data

1 code implementation15 Apr 2015 Christos Tzelepis, Vasileios Mezaris, Ioannis Patras

In this paper, we propose a maximum margin classifier that deals with uncertainty in data input.

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